Copyright (C) by Argonne National Laboratory
    See COPYRIGHT in top-level directory

Automatically generated
  by:   ./maint/extractcvars
  at:   Fri Jan 22 20:18:10 2021 UTC
DO NOT EDIT!!!

This file lists the various environment variables available to change the
behavior of the MPICH library.  These are intended to be used by advanced
users.
---------------------------------------------------------------------------

MPIR_CVAR_ALLGATHER_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_ALLGATHER_SHORT_MSG_SIZE
             MPICH_ALLGATHER_SHORT_MSG_SIZE
    Description: For MPI_Allgather and MPI_Allgatherv, the short message
        algorithm will be used if the send buffer size is < this value (in
        bytes). (See also: MPIR_CVAR_ALLGATHER_LONG_MSG_SIZE)
    Default: 81920

MPIR_CVAR_ALLGATHER_LONG_MSG_SIZE
    Aliases: MPIR_PARAM_ALLGATHER_LONG_MSG_SIZE
             MPICH_ALLGATHER_LONG_MSG_SIZE
    Description: For MPI_Allgather and MPI_Allgatherv, the long message
        algorithm will be used if the send buffer size is >= this value (in
        bytes) (See also: MPIR_CVAR_ALLGATHER_SHORT_MSG_SIZE)
    Default: 524288

MPIR_CVAR_ALLGATHER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ALLGATHER_INTRA_ALGORITHM
             MPICH_ALLGATHER_INTRA_ALGORITHM
    Description: Variable to select allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        brucks             - Force brucks algorithm
        nb                 - Force nonblocking algorithm
        recursive_doubling - Force recursive doubling algorithm
        ring               - Force ring algorithm
    Default: MPIR_CVAR_ALLGATHER_INTRA_ALGORITHM_auto

MPIR_CVAR_ALLGATHER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ALLGATHER_INTER_ALGORITHM
             MPICH_ALLGATHER_INTER_ALGORITHM
    Description: Variable to select allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        local_gather_remote_bcast - Force local-gather-remote-bcast
        algorithm
        nb                        - Force nonblocking algorithm
    Default: MPIR_CVAR_ALLGATHER_INTER_ALGORITHM_auto

MPIR_CVAR_ALLGATHER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ALLGATHER_DEVICE_COLLECTIVE
             MPICH_ALLGATHER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Allgather will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ALLGATHERV_PIPELINE_MSG_SIZE
    Aliases: MPIR_PARAM_ALLGATHERV_PIPELINE_MSG_SIZE
             MPICH_ALLGATHERV_PIPELINE_MSG_SIZE
    Description: The smallest message size that will be used for the
        pipelined, large-message, ring algorithm in the MPI_Allgatherv
        implementation.
    Default: 32768

MPIR_CVAR_ALLGATHERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ALLGATHERV_INTRA_ALGORITHM
             MPICH_ALLGATHERV_INTRA_ALGORITHM
    Description: Variable to select allgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        brucks             - Force brucks algorithm
        nb                 - Force nonblocking algorithm
        recursive_doubling - Force recursive doubling algorithm
        ring               - Force ring algorithm
    Default: MPIR_CVAR_ALLGATHERV_INTRA_ALGORITHM_auto

MPIR_CVAR_ALLGATHERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ALLGATHERV_INTER_ALGORITHM
             MPICH_ALLGATHERV_INTER_ALGORITHM
    Description: Variable to select allgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                        - Force nonblocking algorithm
        remote_gather_local_bcast - Force remote-gather-local-bcast
        algorithm
    Default: MPIR_CVAR_ALLGATHERV_INTER_ALGORITHM_auto

MPIR_CVAR_ALLGATHERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ALLGATHERV_DEVICE_COLLECTIVE
             MPICH_ALLGATHERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Allgatherv will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ALLREDUCE_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_ALLREDUCE_SHORT_MSG_SIZE
             MPICH_ALLREDUCE_SHORT_MSG_SIZE
    Description: the short message algorithm will be used if the send
        buffer size is <= this value (in bytes)
    Default: 2048

MPIR_CVAR_MAX_SMP_ALLREDUCE_MSG_SIZE
    Aliases: MPIR_PARAM_MAX_SMP_ALLREDUCE_MSG_SIZE
             MPICH_MAX_SMP_ALLREDUCE_MSG_SIZE
    Description: Maximum message size for which SMP-aware allreduce is
        used.  A value of '0' uses SMP-aware allreduce for all message
        sizes.
    Default: 0

MPIR_CVAR_ALLREDUCE_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ALLREDUCE_INTRA_ALGORITHM
             MPICH_ALLREDUCE_INTRA_ALGORITHM
    Description: Variable to select allreduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                       - Force nonblocking algorithm
        smp                      - Force smp algorithm
        recursive_doubling       - Force recursive doubling algorithm
        reduce_scatter_allgather - Force reduce scatter allgather algorithm
    Default: MPIR_CVAR_ALLREDUCE_INTRA_ALGORITHM_auto

MPIR_CVAR_ALLREDUCE_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ALLREDUCE_INTER_ALGORITHM
             MPICH_ALLREDUCE_INTER_ALGORITHM
    Description: Variable to select allreduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                    - Force nonblocking algorithm
        reduce_exchange_bcast - Force reduce-exchange-bcast algorithm
    Default: MPIR_CVAR_ALLREDUCE_INTER_ALGORITHM_auto

MPIR_CVAR_ALLREDUCE_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ALLREDUCE_DEVICE_COLLECTIVE
             MPICH_ALLREDUCE_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Allreduce will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ALLTOALL_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_ALLTOALL_SHORT_MSG_SIZE
             MPICH_ALLTOALL_SHORT_MSG_SIZE
    Description: the short message algorithm will be used if the
        per-destination message size (sendcount*size(sendtype)) is <= this
        value (See also: MPIR_CVAR_ALLTOALL_MEDIUM_MSG_SIZE)
    Default: 256

MPIR_CVAR_ALLTOALL_MEDIUM_MSG_SIZE
    Aliases: MPIR_PARAM_ALLTOALL_MEDIUM_MSG_SIZE
             MPICH_ALLTOALL_MEDIUM_MSG_SIZE
    Description: the medium message algorithm will be used if the
        per-destination message size (sendcount*size(sendtype)) is <= this
        value and larger than MPIR_CVAR_ALLTOALL_SHORT_MSG_SIZE (See also:
        MPIR_CVAR_ALLTOALL_SHORT_MSG_SIZE)
    Default: 32768

MPIR_CVAR_ALLTOALL_THROTTLE
    Aliases: MPIR_PARAM_ALLTOALL_THROTTLE
             MPICH_ALLTOALL_THROTTLE
    Description: max no. of irecvs/isends posted at a time in some alltoall
        algorithms. Setting it to 0 causes all irecvs/isends to be posted
        at once
    Default: 32

MPIR_CVAR_ALLTOALL_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ALLTOALL_INTRA_ALGORITHM
             MPICH_ALLTOALL_INTRA_ALGORITHM
    Description: Variable to select alltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        brucks                    - Force brucks algorithm
        nb                        - Force nonblocking algorithm
        pairwise                  - Force pairwise algorithm
        pairwise_sendrecv_replace - Force pairwise sendrecv replace
        algorithm
        scattered                 - Force scattered algorithm
    Default: MPIR_CVAR_ALLTOALL_INTRA_ALGORITHM_auto

MPIR_CVAR_ALLTOALL_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ALLTOALL_INTER_ALGORITHM
             MPICH_ALLTOALL_INTER_ALGORITHM
    Description: Variable to select alltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                - Force nonblocking algorithm
        pairwise_exchange - Force pairwise exchange algorithm
    Default: MPIR_CVAR_ALLTOALL_INTER_ALGORITHM_auto

MPIR_CVAR_ALLTOALL_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ALLTOALL_DEVICE_COLLECTIVE
             MPICH_ALLTOALL_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Alltoall will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ALLTOALLV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ALLTOALLV_INTRA_ALGORITHM
             MPICH_ALLTOALLV_INTRA_ALGORITHM
    Description: Variable to select alltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                        - Force nonblocking algorithm
        pairwise_sendrecv_replace - Force pairwise_sendrecv_replace
        algorithm
        scattered                 - Force scattered algorithm
    Default: MPIR_CVAR_ALLTOALLV_INTRA_ALGORITHM_auto

MPIR_CVAR_ALLTOALLV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ALLTOALLV_INTER_ALGORITHM
             MPICH_ALLTOALLV_INTER_ALGORITHM
    Description: Variable to select alltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        pairwise_exchange - Force pairwise exchange algorithm
        nb                - Force nonblocking algorithm
    Default: MPIR_CVAR_ALLTOALLV_INTER_ALGORITHM_auto

MPIR_CVAR_ALLTOALLV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ALLTOALLV_DEVICE_COLLECTIVE
             MPICH_ALLTOALLV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Alltoallv will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ALLTOALLW_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ALLTOALLW_INTRA_ALGORITHM
             MPICH_ALLTOALLW_INTRA_ALGORITHM
    Description: Variable to select alltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                        - Force nonblocking algorithm
        pairwise_sendrecv_replace - Force pairwise sendrecv replace
        algorithm
        scattered                 - Force scattered algorithm
    Default: MPIR_CVAR_ALLTOALLW_INTRA_ALGORITHM_auto

MPIR_CVAR_ALLTOALLW_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ALLTOALLW_INTER_ALGORITHM
             MPICH_ALLTOALLW_INTER_ALGORITHM
    Description: Variable to select alltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                - Force nonblocking algorithm
        pairwise_exchange - Force pairwise exchange algorithm
    Default: MPIR_CVAR_ALLTOALLW_INTER_ALGORITHM_auto

MPIR_CVAR_ALLTOALLW_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ALLTOALLW_DEVICE_COLLECTIVE
             MPICH_ALLTOALLW_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Alltoallw will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_BARRIER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_BARRIER_INTRA_ALGORITHM
             MPICH_BARRIER_INTRA_ALGORITHM
    Description: Variable to select barrier algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb            - Force nonblocking algorithm
        dissemination - Force dissemination algorithm
    Default: MPIR_CVAR_BARRIER_INTRA_ALGORITHM_auto

MPIR_CVAR_BARRIER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_BARRIER_INTER_ALGORITHM
             MPICH_BARRIER_INTER_ALGORITHM
    Description: Variable to select barrier algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        bcast - Force bcast algorithm
        nb    - Force nonblocking algorithm
    Default: MPIR_CVAR_BARRIER_INTER_ALGORITHM_auto

MPIR_CVAR_BARRIER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_BARRIER_DEVICE_COLLECTIVE
             MPICH_BARRIER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Barrier will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_BCAST_MIN_PROCS
    Aliases: MPIR_PARAM_BCAST_MIN_PROCS
             MPICH_BCAST_MIN_PROCS
    Description: Let's define short messages as messages with size <
        MPIR_CVAR_BCAST_SHORT_MSG_SIZE, and medium messages as messages
        with size >= MPIR_CVAR_BCAST_SHORT_MSG_SIZE but <
        MPIR_CVAR_BCAST_LONG_MSG_SIZE, and long messages as messages with
        size >= MPIR_CVAR_BCAST_LONG_MSG_SIZE. The broadcast algorithms
        selection procedure is as follows. For short messages or when the
        number of processes is < MPIR_CVAR_BCAST_MIN_PROCS, we do broadcast
        using the binomial tree algorithm. Otherwise, for medium messages
        and with a power-of-two number of processes, we do broadcast based
        on a scatter followed by a recursive doubling allgather algorithm.
        Otherwise, for long messages or with non power-of-two number of
        processes, we do broadcast based on a scatter followed by a ring
        allgather algorithm. (See also: MPIR_CVAR_BCAST_SHORT_MSG_SIZE,
        MPIR_CVAR_BCAST_LONG_MSG_SIZE)
    Default: 8

MPIR_CVAR_BCAST_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_BCAST_SHORT_MSG_SIZE
             MPICH_BCAST_SHORT_MSG_SIZE
    Description: Let's define short messages as messages with size <
        MPIR_CVAR_BCAST_SHORT_MSG_SIZE, and medium messages as messages
        with size >= MPIR_CVAR_BCAST_SHORT_MSG_SIZE but <
        MPIR_CVAR_BCAST_LONG_MSG_SIZE, and long messages as messages with
        size >= MPIR_CVAR_BCAST_LONG_MSG_SIZE. The broadcast algorithms
        selection procedure is as follows. For short messages or when the
        number of processes is < MPIR_CVAR_BCAST_MIN_PROCS, we do broadcast
        using the binomial tree algorithm. Otherwise, for medium messages
        and with a power-of-two number of processes, we do broadcast based
        on a scatter followed by a recursive doubling allgather algorithm.
        Otherwise, for long messages or with non power-of-two number of
        processes, we do broadcast based on a scatter followed by a ring
        allgather algorithm. (See also: MPIR_CVAR_BCAST_MIN_PROCS,
        MPIR_CVAR_BCAST_LONG_MSG_SIZE)
    Default: 12288

MPIR_CVAR_BCAST_LONG_MSG_SIZE
    Aliases: MPIR_PARAM_BCAST_LONG_MSG_SIZE
             MPICH_BCAST_LONG_MSG_SIZE
    Description: Let's define short messages as messages with size <
        MPIR_CVAR_BCAST_SHORT_MSG_SIZE, and medium messages as messages
        with size >= MPIR_CVAR_BCAST_SHORT_MSG_SIZE but <
        MPIR_CVAR_BCAST_LONG_MSG_SIZE, and long messages as messages with
        size >= MPIR_CVAR_BCAST_LONG_MSG_SIZE. The broadcast algorithms
        selection procedure is as follows. For short messages or when the
        number of processes is < MPIR_CVAR_BCAST_MIN_PROCS, we do broadcast
        using the binomial tree algorithm. Otherwise, for medium messages
        and with a power-of-two number of processes, we do broadcast based
        on a scatter followed by a recursive doubling allgather algorithm.
        Otherwise, for long messages or with non power-of-two number of
        processes, we do broadcast based on a scatter followed by a ring
        allgather algorithm. (See also: MPIR_CVAR_BCAST_MIN_PROCS,
        MPIR_CVAR_BCAST_SHORT_MSG_SIZE)
    Default: 524288

MPIR_CVAR_MAX_SMP_BCAST_MSG_SIZE
    Aliases: MPIR_PARAM_MAX_SMP_BCAST_MSG_SIZE
             MPICH_MAX_SMP_BCAST_MSG_SIZE
    Description: Maximum message size for which SMP-aware broadcast is
        used.  A value of '0' uses SMP-aware broadcast for all message
        sizes.
    Default: 0

MPIR_CVAR_BCAST_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_BCAST_INTRA_ALGORITHM
             MPICH_BCAST_INTRA_ALGORITHM
    Description: Variable to select bcast algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        binomial                                - Force Binomial Tree
        nb                                      - Force nonblocking
        algorithm
        smp                                     - Force smp algorithm
        scatter_recursive_doubling_allgather    - Force Scatter
        Recursive-Doubling Allgather
        scatter_ring_allgather                  - Force Scatter Ring
    Default: MPIR_CVAR_BCAST_INTRA_ALGORITHM_auto

MPIR_CVAR_BCAST_INTER_ALGORITHM
    Aliases: MPIR_PARAM_BCAST_INTER_ALGORITHM
             MPICH_BCAST_INTER_ALGORITHM
    Description: Variable to select bcast algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                      - Force nonblocking algorithm
        remote_send_local_bcast - Force remote-send-local-bcast algorithm
    Default: MPIR_CVAR_BCAST_INTER_ALGORITHM_auto

MPIR_CVAR_BCAST_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_BCAST_DEVICE_COLLECTIVE
             MPICH_BCAST_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Bcast will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_EXSCAN_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_EXSCAN_INTRA_ALGORITHM
             MPICH_EXSCAN_INTRA_ALGORITHM
    Description: Variable to select allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                 - Force nonblocking algorithm
        recursive_doubling - Force recursive doubling algorithm
    Default: MPIR_CVAR_EXSCAN_INTRA_ALGORITHM_auto

MPIR_CVAR_EXSCAN_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_EXSCAN_DEVICE_COLLECTIVE
             MPICH_EXSCAN_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Exscan will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_GATHER_INTER_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_GATHER_INTER_SHORT_MSG_SIZE
             MPICH_GATHER_INTER_SHORT_MSG_SIZE
    Description: use the short message algorithm for intercommunicator
        MPI_Gather if the send buffer size is < this value (in bytes) (See
        also: MPIR_CVAR_GATHER_VSMALL_MSG_SIZE)
    Default: 2048

MPIR_CVAR_GATHER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_GATHER_INTRA_ALGORITHM
             MPICH_GATHER_INTRA_ALGORITHM
    Description: Variable to select gather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        binomial - Force binomial algorithm
        nb       - Force nonblocking algorithm
    Default: MPIR_CVAR_GATHER_INTRA_ALGORITHM_auto

MPIR_CVAR_GATHER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_GATHER_INTER_ALGORITHM
             MPICH_GATHER_INTER_ALGORITHM
    Description: Variable to select gather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        linear                   - Force linear algorithm
        local_gather_remote_send - Force local-gather-remote-send algorithm
        nb                       - Force nonblocking algorithm
    Default: MPIR_CVAR_GATHER_INTER_ALGORITHM_auto

MPIR_CVAR_GATHER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_GATHER_DEVICE_COLLECTIVE
             MPICH_GATHER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Gather will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_GATHER_VSMALL_MSG_SIZE
    Aliases: MPIR_PARAM_GATHER_VSMALL_MSG_SIZE
             MPICH_GATHER_VSMALL_MSG_SIZE
    Description: use a temporary buffer for intracommunicator MPI_Gather if
        the send buffer size is < this value (in bytes) (See also:
        MPIR_CVAR_GATHER_INTER_SHORT_MSG_SIZE)
    Default: 1024

MPIR_CVAR_GATHERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_GATHERV_INTRA_ALGORITHM
             MPICH_GATHERV_INTRA_ALGORITHM
    Description: Variable to select gatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        linear - Force linear algorithm
        nb     - Force nonblocking algorithm
    Default: MPIR_CVAR_GATHERV_INTRA_ALGORITHM_auto

MPIR_CVAR_GATHERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_GATHERV_INTER_ALGORITHM
             MPICH_GATHERV_INTER_ALGORITHM
    Description: Variable to select gatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        linear - Force linear algorithm
        nb     - Force nonblocking algorithm
    Default: MPIR_CVAR_GATHERV_INTER_ALGORITHM_auto

MPIR_CVAR_GATHERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_GATHERV_DEVICE_COLLECTIVE
             MPICH_GATHERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Gatherv will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_GATHERV_INTER_SSEND_MIN_PROCS
    Aliases: MPIR_PARAM_GATHERV_INTER_SSEND_MIN_PROCS
             MPICH_GATHERV_INTER_SSEND_MIN_PROCS
    Description: Use Ssend (synchronous send) for intercommunicator
        MPI_Gatherv if the "group B" size is >= this value.  Specifying
        "-1" always avoids using Ssend.  For backwards compatibility,
        specifying "0" uses the default value.
    Default: 32

MPIR_CVAR_IALLGATHER_RECEXCH_KVAL
    Aliases: MPIR_PARAM_IALLGATHER_RECEXCH_KVAL
             MPICH_IALLGATHER_RECEXCH_KVAL
    Description: k value for recursive exchange based iallgather
    Default: 2

MPIR_CVAR_IALLGATHER_BRUCKS_KVAL
    Aliases: MPIR_PARAM_IALLGATHER_BRUCKS_KVAL
             MPICH_IALLGATHER_BRUCKS_KVAL
    Description: k value for radix in brucks based iallgather
    Default: 2

MPIR_CVAR_IALLGATHER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IALLGATHER_INTRA_ALGORITHM
             MPICH_IALLGATHER_INTRA_ALGORITHM
    Description: Variable to select iallgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_ring               - Force ring algorithm
        sched_brucks             - Force brucks algorithm
        sched_recursive_doubling - Force recursive doubling algorithm
        gentran_ring       - Force generic transport ring algorithm
        gentran_brucks     - Force generic transport based brucks algorithm
        gentran_recexch_doubling - Force generic transport recursive
        exchange with neighbours doubling in distance in each phase
        gentran_recexch_halving  - Force generic transport recursive
        exchange with neighbours halving in distance in each phase
    Default: MPIR_CVAR_IALLGATHER_INTRA_ALGORITHM_auto

MPIR_CVAR_IALLGATHER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IALLGATHER_INTER_ALGORITHM
             MPICH_IALLGATHER_INTER_ALGORITHM
    Description: Variable to select iallgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_local_gather_remote_bcast - Force local-gather-remote-bcast
        algorithm
    Default: MPIR_CVAR_IALLGATHER_INTER_ALGORITHM_auto

MPIR_CVAR_IALLGATHER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IALLGATHER_DEVICE_COLLECTIVE
             MPICH_IALLGATHER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iallgather will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IALLGATHERV_RECEXCH_KVAL
    Aliases: MPIR_PARAM_IALLGATHERV_RECEXCH_KVAL
             MPICH_IALLGATHERV_RECEXCH_KVAL
    Description: k value for recursive exchange based iallgatherv
    Default: 2

MPIR_CVAR_IALLGATHERV_BRUCKS_KVAL
    Aliases: MPIR_PARAM_IALLGATHERV_BRUCKS_KVAL
             MPICH_IALLGATHERV_BRUCKS_KVAL
    Description: k value for radix in brucks based iallgatherv
    Default: 2

MPIR_CVAR_IALLGATHERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IALLGATHERV_INTRA_ALGORITHM
             MPICH_IALLGATHERV_INTRA_ALGORITHM
    Description: Variable to select iallgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_brucks             - Force brucks algorithm
        sched_recursive_doubling - Force recursive doubling algorithm
        sched_ring               - Force ring algorithm
        gentran_recexch_doubling - Force generic transport recursive
        exchange with neighbours doubling in distance in each phase
        gentran_recexch_halving  - Force generic transport recursive
        exchange with neighbours halving in distance in each phase
        gentran_ring             - Force generic transport ring algorithm
        gentran_brucks           - Force generic transport based brucks
        algorithm
    Default: MPIR_CVAR_IALLGATHERV_INTRA_ALGORITHM_auto

MPIR_CVAR_IALLGATHERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IALLGATHERV_INTER_ALGORITHM
             MPICH_IALLGATHERV_INTER_ALGORITHM
    Description: Variable to select iallgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_remote_gather_local_bcast - Force remote-gather-local-bcast
        algorithm
    Default: MPIR_CVAR_IALLGATHERV_INTER_ALGORITHM_auto

MPIR_CVAR_IALLGATHERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IALLGATHERV_DEVICE_COLLECTIVE
             MPICH_IALLGATHERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iallgatherv will allow
        the device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IALLREDUCE_TREE_KVAL
    Aliases: MPIR_PARAM_IALLREDUCE_TREE_KVAL
             MPICH_IALLREDUCE_TREE_KVAL
    Description: k value for tree based iallreduce (for tree_kary and
        tree_knomial)
    Default: 2

MPIR_CVAR_IALLREDUCE_TREE_TYPE
    Aliases: MPIR_PARAM_IALLREDUCE_TREE_TYPE
             MPICH_IALLREDUCE_TREE_TYPE
    Description: Tree type for tree based ibcast kary      - kary tree type
        knomial_1 - knomial_1 tree type knomial_2 - knomial_2 tree type
    Default: "kary"

MPIR_CVAR_IALLREDUCE_TREE_PIPELINE_CHUNK_SIZE
    Aliases: MPIR_PARAM_IALLREDUCE_TREE_PIPELINE_CHUNK_SIZE
             MPICH_IALLREDUCE_TREE_PIPELINE_CHUNK_SIZE
    Description: Maximum chunk size (in bytes) for pipelining in tree based
        iallreduce. Default value is 0, that is, no pipelining by default
    Default: 0

MPIR_CVAR_IALLREDUCE_TREE_BUFFER_PER_CHILD
    Aliases: MPIR_PARAM_IALLREDUCE_TREE_BUFFER_PER_CHILD
             MPICH_IALLREDUCE_TREE_BUFFER_PER_CHILD
    Description: If set to true, a rank in tree_kary and tree_knomial
        algorithms will allocate a dedicated buffer for every child it
        receives data from. This would mean more memory consumption but it
        would allow preposting of the receives and hence reduce the number
        of unexpected messages. If set to false, there is only one buffer
        that is used to receive the data from all the children. The
        receives are therefore serialized, that is, only one receive can be
        posted at a time.
    Default: 0

MPIR_CVAR_IALLREDUCE_RECEXCH_KVAL
    Aliases: MPIR_PARAM_IALLREDUCE_RECEXCH_KVAL
             MPICH_IALLREDUCE_RECEXCH_KVAL
    Description: k value for recursive exchange based iallreduce
    Default: 2

MPIR_CVAR_IALLREDUCE_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IALLREDUCE_INTRA_ALGORITHM
             MPICH_IALLREDUCE_INTRA_ALGORITHM
    Description: Variable to select iallreduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_naive                      - Force naive algorithm
        sched_smp                        - Force smp algorithm
        sched_recursive_doubling         - Force recursive doubling
        algorithm
        sched_reduce_scatter_allgather   - Force reduce scatter allgather
        algorithm
        gentran_recexch_single_buffer    - Force generic transport
        recursive exchange with single buffer for receives
        gentran_recexch_multiple_buffer  - Force generic transport
        recursive exchange with multiple buffers for receives
        gentran_tree                     - Force generic transport tree
        algorithm
        gentran_ring                     - Force generic transport ring
        algorithm
        gentran_recexch_reduce_scatter_recexch_allgatherv  - Force generic
        transport recursive exchange with reduce scatter and allgatherv
    Default: MPIR_CVAR_IALLREDUCE_INTRA_ALGORITHM_auto

MPIR_CVAR_IALLREDUCE_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IALLREDUCE_INTER_ALGORITHM
             MPICH_IALLREDUCE_INTER_ALGORITHM
    Description: Variable to select iallreduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_remote_reduce_local_bcast - Force remote-reduce-local-bcast
        algorithm
    Default: MPIR_CVAR_IALLREDUCE_INTER_ALGORITHM_auto

MPIR_CVAR_IALLREDUCE_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IALLREDUCE_DEVICE_COLLECTIVE
             MPICH_IALLREDUCE_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iallreduce will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IALLTOALL_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IALLTOALL_INTRA_ALGORITHM
             MPICH_IALLTOALL_INTRA_ALGORITHM
    Description: Variable to select ialltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_brucks            - Force brucks algorithm
        sched_inplace           - Force inplace algorithm
        sched_pairwise          - Force pairwise algorithm
        sched_permuted_sendrecv - Force permuted sendrecv algorithm
        gentran_ring            - Force generic transport based ring
        algorithm
        gentran_brucks          - Force generic transport based brucks
        algorithm
        gentran_scattered       - Force generic transport based scattered
        algorithm
    Default: MPIR_CVAR_IALLTOALL_INTRA_ALGORITHM_auto

MPIR_CVAR_IALLTOALL_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IALLTOALL_INTER_ALGORITHM
             MPICH_IALLTOALL_INTER_ALGORITHM
    Description: Variable to select ialltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_pairwise_exchange - Force pairwise exchange algorithm
    Default: MPIR_CVAR_IALLTOALL_INTER_ALGORITHM_auto

MPIR_CVAR_IALLTOALL_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IALLTOALL_DEVICE_COLLECTIVE
             MPICH_IALLTOALL_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ialltoall will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IALLTOALL_BRUCKS_KVAL
    Aliases: MPIR_PARAM_IALLTOALL_BRUCKS_KVAL
             MPICH_IALLTOALL_BRUCKS_KVAL
    Description: radix (k) value for generic transport brucks based
        ialltoall
    Default: 2

MPIR_CVAR_IALLTOALL_BRUCKS_BUFFER_PER_NBR
    Aliases: MPIR_PARAM_IALLTOALL_BRUCKS_BUFFER_PER_NBR
             MPICH_IALLTOALL_BRUCKS_BUFFER_PER_NBR
    Description: If set to true, the gentran based brucks algorithm will
        allocate dedicated send and receive buffers for every neighbor in
        the brucks algorithm. Otherwise, it would reuse a single buffer for
        sending and receiving data to/from neighbors
    Default: 0

MPIR_CVAR_IALLTOALL_SCATTERED_OUTSTANDING_TASKS
    Aliases: MPIR_PARAM_IALLTOALL_SCATTERED_OUTSTANDING_TASKS
             MPICH_IALLTOALL_SCATTERED_OUTSTANDING_TASKS
    Description: Maximum number of outstanding sends and recvs posted at a
        time
    Default: 64

MPIR_CVAR_IALLTOALL_SCATTERED_BATCH_SIZE
    Aliases: MPIR_PARAM_IALLTOALL_SCATTERED_BATCH_SIZE
             MPICH_IALLTOALL_SCATTERED_BATCH_SIZE
    Description: Number of send/receive tasks that scattered algorithm
        waits for completion before posting another batch of send/receives
        of that size
    Default: 4

MPIR_CVAR_IALLTOALLV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IALLTOALLV_INTRA_ALGORITHM
             MPICH_IALLTOALLV_INTRA_ALGORITHM
    Description: Variable to select ialltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_blocked           - Force blocked algorithm
        sched_inplace           - Force inplace algorithm
        sched_pairwise_exchange - Force pairwise exchange algorithm
        gentran_scattered       - Force generic transport based scattered
        algorithm
        gentran_blocked         - Force generic transport blocked algorithm
        gentran_inplace         - Force generic transport inplace algorithm
    Default: MPIR_CVAR_IALLTOALLV_INTRA_ALGORITHM_auto

MPIR_CVAR_IALLTOALLV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IALLTOALLV_INTER_ALGORITHM
             MPICH_IALLTOALLV_INTER_ALGORITHM
    Description: Variable to select ialltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_pairwise_exchange - Force pairwise exchange algorithm
    Default: MPIR_CVAR_IALLTOALLV_INTER_ALGORITHM_auto

MPIR_CVAR_IALLTOALLV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IALLTOALLV_DEVICE_COLLECTIVE
             MPICH_IALLTOALLV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ialltoallv will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IALLTOALLV_SCATTERED_OUTSTANDING_TASKS
    Aliases: MPIR_PARAM_IALLTOALLV_SCATTERED_OUTSTANDING_TASKS
             MPICH_IALLTOALLV_SCATTERED_OUTSTANDING_TASKS
    Description: Maximum number of outstanding sends and recvs posted at a
        time
    Default: 64

MPIR_CVAR_IALLTOALLV_SCATTERED_BATCH_SIZE
    Aliases: MPIR_PARAM_IALLTOALLV_SCATTERED_BATCH_SIZE
             MPICH_IALLTOALLV_SCATTERED_BATCH_SIZE
    Description: Number of send/receive tasks that scattered algorithm
        waits for completion before posting another batch of send/receives
        of that size
    Default: 4

MPIR_CVAR_IALLTOALLW_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IALLTOALLW_INTRA_ALGORITHM
             MPICH_IALLTOALLW_INTRA_ALGORITHM
    Description: Variable to select ialltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_blocked           - Force blocked algorithm
        sched_inplace           - Force inplace algorithm
        gentran_blocked   - Force genereic transport based blocked
        algorithm
        gentran_inplace   - Force genereic transport based inplace
        algorithm
    Default: MPIR_CVAR_IALLTOALLW_INTRA_ALGORITHM_auto

MPIR_CVAR_IALLTOALLW_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IALLTOALLW_INTER_ALGORITHM
             MPICH_IALLTOALLW_INTER_ALGORITHM
    Description: Variable to select ialltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_pairwise_exchange - Force pairwise exchange algorithm
    Default: MPIR_CVAR_IALLTOALLW_INTER_ALGORITHM_auto

MPIR_CVAR_IALLTOALLW_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IALLTOALLW_DEVICE_COLLECTIVE
             MPICH_IALLTOALLW_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ialltoallw will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IBARRIER_RECEXCH_KVAL
    Aliases: MPIR_PARAM_IBARRIER_RECEXCH_KVAL
             MPICH_IBARRIER_RECEXCH_KVAL
    Description: k value for recursive exchange based ibarrier
    Default: 2

MPIR_CVAR_IBARRIER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IBARRIER_INTRA_ALGORITHM
             MPICH_IBARRIER_INTRA_ALGORITHM
    Description: Variable to select ibarrier algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_recursive_doubling - Force recursive doubling algorithm
        gentran_recexch          - Force generic transport based recursive
        exchange algorithm
    Default: MPIR_CVAR_IBARRIER_INTRA_ALGORITHM_auto

MPIR_CVAR_IBARRIER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IBARRIER_INTER_ALGORITHM
             MPICH_IBARRIER_INTER_ALGORITHM
    Description: Variable to select ibarrier algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_bcast - Force bcast algorithm
    Default: MPIR_CVAR_IBARRIER_INTER_ALGORITHM_auto

MPIR_CVAR_IBARRIER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IBARRIER_DEVICE_COLLECTIVE
             MPICH_IBARRIER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ibarrier will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IBCAST_TREE_KVAL
    Aliases: MPIR_PARAM_IBCAST_TREE_KVAL
             MPICH_IBCAST_TREE_KVAL
    Description: k value for tree (kary, knomial, etc.) based ibcast
    Default: 2

MPIR_CVAR_IBCAST_TREE_TYPE
    Aliases: MPIR_PARAM_IBCAST_TREE_TYPE
             MPICH_IBCAST_TREE_TYPE
    Description: Tree type for tree based ibcast kary      - kary tree type
        knomial_1 - knomial_1 tree type knomial_2 - knomial_2 tree type
    Default: "kary"

MPIR_CVAR_IBCAST_TREE_PIPELINE_CHUNK_SIZE
    Aliases: MPIR_PARAM_IBCAST_TREE_PIPELINE_CHUNK_SIZE
             MPICH_IBCAST_TREE_PIPELINE_CHUNK_SIZE
    Description: Maximum chunk size (in bytes) for pipelining in tree based
        ibcast. Default value is 0, that is, no pipelining by default
    Default: 0

MPIR_CVAR_IBCAST_RING_CHUNK_SIZE
    Aliases: MPIR_PARAM_IBCAST_RING_CHUNK_SIZE
             MPICH_IBCAST_RING_CHUNK_SIZE
    Description: Maximum chunk size (in bytes) for pipelining in ibcast
        ring algorithm. Default value is 0, that is, no pipelining by
        default
    Default: 0

MPIR_CVAR_IBCAST_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IBCAST_INTRA_ALGORITHM
             MPICH_IBCAST_INTRA_ALGORITHM
    Description: Variable to select ibcast algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_binomial                             - Force Binomial
        algorithm
        sched_smp                                  - Force smp algorithm
        sched_scatter_recursive_doubling_allgather - Force Scatter
        Recursive Doubling Allgather algorithm
        sched_scatter_ring_allgather               - Force Scatter Ring
        Allgather algorithm
        gentran_tree                               - Force Generic
        Transport Tree algorithm
        gentran_scatterv_recexch_allgatherv        - Force Generic
        Transport Scatterv followed by Recursive Exchange Allgatherv
        algorithm
        gentran_ring                               - Force Generic
        Transport Ring algorithm
    Default: MPIR_CVAR_IBCAST_INTRA_ALGORITHM_auto

MPIR_CVAR_IBCAST_SCATTERV_KVAL
    Aliases: MPIR_PARAM_IBCAST_SCATTERV_KVAL
             MPICH_IBCAST_SCATTERV_KVAL
    Description: k value for tree based scatter in
        scatter_recexch_allgather algorithm
    Default: 2

MPIR_CVAR_IBCAST_ALLGATHERV_RECEXCH_KVAL
    Aliases: MPIR_PARAM_IBCAST_ALLGATHERV_RECEXCH_KVAL
             MPICH_IBCAST_ALLGATHERV_RECEXCH_KVAL
    Description: k value for recursive exchange based allgather in
        scatter_recexch_allgather algorithm
    Default: 2

MPIR_CVAR_IBCAST_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IBCAST_INTER_ALGORITHM
             MPICH_IBCAST_INTER_ALGORITHM
    Description: Variable to select ibcast algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_flat - Force flat algorithm
    Default: MPIR_CVAR_IBCAST_INTER_ALGORITHM_auto

MPIR_CVAR_IBCAST_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IBCAST_DEVICE_COLLECTIVE
             MPICH_IBCAST_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ibcast will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IEXSCAN_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IEXSCAN_INTRA_ALGORITHM
             MPICH_IEXSCAN_INTRA_ALGORITHM
    Description: Variable to select iexscan algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_recursive_doubling - Force recursive doubling algorithm
    Default: MPIR_CVAR_IEXSCAN_INTRA_ALGORITHM_auto

MPIR_CVAR_IEXSCAN_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IEXSCAN_DEVICE_COLLECTIVE
             MPICH_IEXSCAN_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iexscan will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IGATHER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IGATHER_INTRA_ALGORITHM
             MPICH_IGATHER_INTRA_ALGORITHM
    Description: Variable to select igather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_binomial     - Force binomial algorithm
        gentran_tree       - Force genetric transport based tree algorithm
    Default: MPIR_CVAR_IGATHER_INTRA_ALGORITHM_auto

MPIR_CVAR_IGATHER_TREE_KVAL
    Aliases: MPIR_PARAM_IGATHER_TREE_KVAL
             MPICH_IGATHER_TREE_KVAL
    Description: k value for tree based igather
    Default: 2

MPIR_CVAR_IGATHER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IGATHER_INTER_ALGORITHM
             MPICH_IGATHER_INTER_ALGORITHM
    Description: Variable to select igather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_long  - Force long inter algorithm
        sched_short - Force short inter algorithm
    Default: MPIR_CVAR_IGATHER_INTER_ALGORITHM_auto

MPIR_CVAR_IGATHER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IGATHER_DEVICE_COLLECTIVE
             MPICH_IGATHER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Igather will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IGATHERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IGATHERV_INTRA_ALGORITHM
             MPICH_IGATHERV_INTRA_ALGORITHM
    Description: Variable to select igatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear         - Force linear algorithm
        gentran_linear       - Force generic transport based linear
        algorithm
    Default: MPIR_CVAR_IGATHERV_INTRA_ALGORITHM_auto

MPIR_CVAR_IGATHERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IGATHERV_INTER_ALGORITHM
             MPICH_IGATHERV_INTER_ALGORITHM
    Description: Variable to select igatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear - Force linear algorithm
    Default: MPIR_CVAR_IGATHERV_INTER_ALGORITHM_auto

MPIR_CVAR_IGATHERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IGATHERV_DEVICE_COLLECTIVE
             MPICH_IGATHERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Igatherv will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_INEIGHBOR_ALLGATHER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLGATHER_INTRA_ALGORITHM
             MPICH_INEIGHBOR_ALLGATHER_INTRA_ALGORITHM
    Description: Variable to select ineighbor_allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear    - Force linear algorithm
        gentran_linear  - Force generic transport based linear algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLGATHER_INTRA_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLGATHER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLGATHER_INTER_ALGORITHM
             MPICH_INEIGHBOR_ALLGATHER_INTER_ALGORITHM
    Description: Variable to select ineighbor_allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear    - Force linear algorithm
        gentran_linear  - Force generic transport based linear algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLGATHER_INTER_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLGATHER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_INEIGHBOR_ALLGATHER_DEVICE_COLLECTIVE
             MPICH_INEIGHBOR_ALLGATHER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ineighbor_allgather will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_INEIGHBOR_ALLGATHERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLGATHERV_INTRA_ALGORITHM
             MPICH_INEIGHBOR_ALLGATHERV_INTRA_ALGORITHM
    Description: Variable to select ineighbor_allgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear        - Force generic transport based linear
        algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLGATHERV_INTRA_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLGATHERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLGATHERV_INTER_ALGORITHM
             MPICH_INEIGHBOR_ALLGATHERV_INTER_ALGORITHM
    Description: Variable to select ineighbor_allgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear        - Force generic transport based linear
        algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLGATHERV_INTER_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLGATHERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_INEIGHBOR_ALLGATHERV_DEVICE_COLLECTIVE
             MPICH_INEIGHBOR_ALLGATHERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ineighbor_allgatherv will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_INEIGHBOR_ALLTOALL_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALL_INTRA_ALGORITHM
             MPICH_INEIGHBOR_ALLTOALL_INTRA_ALGORITHM
    Description: Variable to select ineighbor_alltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear        - Force generic transport based linear
        algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLTOALL_INTRA_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLTOALL_INTER_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALL_INTER_ALGORITHM
             MPICH_INEIGHBOR_ALLTOALL_INTER_ALGORITHM
    Description: Variable to select ineighbor_alltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear        - Force generic transport based linear
        algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLTOALL_INTER_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLTOALL_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALL_DEVICE_COLLECTIVE
             MPICH_INEIGHBOR_ALLTOALL_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ineighbor_alltoall will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_INEIGHBOR_ALLTOALLV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALLV_INTRA_ALGORITHM
             MPICH_INEIGHBOR_ALLTOALLV_INTRA_ALGORITHM
    Description: Variable to select ineighbor_alltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear  - Force generic transport based linear algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLTOALLV_INTRA_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLTOALLV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALLV_INTER_ALGORITHM
             MPICH_INEIGHBOR_ALLTOALLV_INTER_ALGORITHM
    Description: Variable to select ineighbor_alltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear  - Force generic transport based linear algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLTOALLV_INTER_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLTOALLV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALLV_DEVICE_COLLECTIVE
             MPICH_INEIGHBOR_ALLTOALLV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ineighbor_alltoallv will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_INEIGHBOR_ALLTOALLW_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALLW_INTRA_ALGORITHM
             MPICH_INEIGHBOR_ALLTOALLW_INTRA_ALGORITHM
    Description: Variable to select ineighbor_alltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear        - Force generic transport based linear
        algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLTOALLW_INTRA_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLTOALLW_INTER_ALGORITHM
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALLW_INTER_ALGORITHM
             MPICH_INEIGHBOR_ALLTOALLW_INTER_ALGORITHM
    Description: Variable to select ineighbor_alltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear          - Force linear algorithm
        gentran_linear        - Force generic transport based linear
        algorithm
    Default: MPIR_CVAR_INEIGHBOR_ALLTOALLW_INTER_ALGORITHM_auto

MPIR_CVAR_INEIGHBOR_ALLTOALLW_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_INEIGHBOR_ALLTOALLW_DEVICE_COLLECTIVE
             MPICH_INEIGHBOR_ALLTOALLW_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ineighbor_alltoallw will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IREDUCE_TREE_KVAL
    Aliases: MPIR_PARAM_IREDUCE_TREE_KVAL
             MPICH_IREDUCE_TREE_KVAL
    Description: k value for tree (kary, knomial, etc.) based ireduce
    Default: 2

MPIR_CVAR_IREDUCE_TREE_TYPE
    Aliases: MPIR_PARAM_IREDUCE_TREE_TYPE
             MPICH_IREDUCE_TREE_TYPE
    Description: Tree type for tree based ireduce kary      - kary tree
        knomial_1 - knomial_1 tree knomial_2 - knomial_2 tree
    Default: "kary"

MPIR_CVAR_IREDUCE_TREE_PIPELINE_CHUNK_SIZE
    Aliases: MPIR_PARAM_IREDUCE_TREE_PIPELINE_CHUNK_SIZE
             MPICH_IREDUCE_TREE_PIPELINE_CHUNK_SIZE
    Description: Maximum chunk size (in bytes) for pipelining in tree based
        ireduce. Default value is 0, that is, no pipelining by default
    Default: -1

MPIR_CVAR_IREDUCE_RING_CHUNK_SIZE
    Aliases: MPIR_PARAM_IREDUCE_RING_CHUNK_SIZE
             MPICH_IREDUCE_RING_CHUNK_SIZE
    Description: Maximum chunk size (in bytes) for pipelining in ireduce
        ring algorithm. Default value is 0, that is, no pipelining by
        default
    Default: 0

MPIR_CVAR_IREDUCE_TREE_BUFFER_PER_CHILD
    Aliases: MPIR_PARAM_IREDUCE_TREE_BUFFER_PER_CHILD
             MPICH_IREDUCE_TREE_BUFFER_PER_CHILD
    Description: If set to true, a rank in tree algorithms will allocate a
        dedicated buffer for every child it receives data from. This would
        mean more memory consumption but it would allow preposting of the
        receives and hence reduce the number of unexpected messages. If set
        to false, there is only one buffer that is used to receive the data
        from all the children. The receives are therefore serialized, that
        is, only one receive can be posted at a time.
    Default: 0

MPIR_CVAR_IREDUCE_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IREDUCE_INTRA_ALGORITHM
             MPICH_IREDUCE_INTRA_ALGORITHM
    Description: Variable to select ireduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_smp                   - Force smp algorithm
        sched_binomial              - Force binomial algorithm
        sched_reduce_scatter_gather - Force reduce scatter gather algorithm
        gentran_tree                - Force Generic Transport Tree
        gentran_ring                - Force Generic Transport Ring
    Default: MPIR_CVAR_IREDUCE_INTRA_ALGORITHM_auto

MPIR_CVAR_IREDUCE_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IREDUCE_INTER_ALGORITHM
             MPICH_IREDUCE_INTER_ALGORITHM
    Description: Variable to select ireduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_local_reduce_remote_send - Force local-reduce-remote-send
        algorithm
    Default: MPIR_CVAR_IREDUCE_INTER_ALGORITHM_auto

MPIR_CVAR_IREDUCE_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IREDUCE_DEVICE_COLLECTIVE
             MPICH_IREDUCE_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ireduce will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IREDUCE_SCATTER_RECEXCH_KVAL
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_RECEXCH_KVAL
             MPICH_IREDUCE_SCATTER_RECEXCH_KVAL
    Description: k value for recursive exchange based ireduce_scatter
    Default: 2

MPIR_CVAR_IREDUCE_SCATTER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_INTRA_ALGORITHM
             MPICH_IREDUCE_SCATTER_INTRA_ALGORITHM
    Description: Variable to select ireduce_scatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_noncommutative     - Force noncommutative algorithm
        sched_recursive_doubling - Force recursive doubling algorithm
        sched_pairwise           - Force pairwise algorithm
        sched_recursive_halving  - Force recursive halving algorithm
        gentran_recexch          - Force generic transport recursive
        exchange algorithm
    Default: MPIR_CVAR_IREDUCE_SCATTER_INTRA_ALGORITHM_auto

MPIR_CVAR_IREDUCE_SCATTER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_INTER_ALGORITHM
             MPICH_IREDUCE_SCATTER_INTER_ALGORITHM
    Description: Variable to select ireduce_scatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_remote_reduce_local_scatterv - Force
        remote-reduce-local-scatterv algorithm
    Default: MPIR_CVAR_IREDUCE_SCATTER_INTER_ALGORITHM_auto

MPIR_CVAR_IREDUCE_SCATTER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_DEVICE_COLLECTIVE
             MPICH_IREDUCE_SCATTER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ireduce_scatter will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_IREDUCE_SCATTER_BLOCK_RECEXCH_KVAL
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_BLOCK_RECEXCH_KVAL
             MPICH_IREDUCE_SCATTER_BLOCK_RECEXCH_KVAL
    Description: k value for recursive exchange based ireduce_scatter_block
    Default: 2

MPIR_CVAR_IREDUCE_SCATTER_BLOCK_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_BLOCK_INTRA_ALGORITHM
             MPICH_IREDUCE_SCATTER_BLOCK_INTRA_ALGORITHM
    Description: Variable to select ireduce_scatter_block algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_noncommutative     - Force noncommutative algorithm
        sched_recursive_doubling - Force recursive doubling algorithm
        sched_pairwise           - Force pairwise algorithm
        sched_recursive_halving  - Force recursive halving algorithm
        gentran_recexch          - Force generic transport recursive
        exchange algorithm
    Default: MPIR_CVAR_IREDUCE_SCATTER_BLOCK_INTRA_ALGORITHM_auto

MPIR_CVAR_IREDUCE_SCATTER_BLOCK_INTER_ALGORITHM
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_BLOCK_INTER_ALGORITHM
             MPICH_IREDUCE_SCATTER_BLOCK_INTER_ALGORITHM
    Description: Variable to select ireduce_scatter_block algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_remote_reduce_local_scatterv - Force
        remote-reduce-local-scatterv algorithm
    Default: MPIR_CVAR_IREDUCE_SCATTER_BLOCK_INTER_ALGORITHM_auto

MPIR_CVAR_IREDUCE_SCATTER_BLOCK_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_IREDUCE_SCATTER_BLOCK_DEVICE_COLLECTIVE
             MPICH_IREDUCE_SCATTER_BLOCK_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Ireduce_scatter_block
        will allow the device to override the MPIR-level collective
        algorithms.  The device might still call the MPIR-level algorithms
        manually.  If set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ISCAN_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ISCAN_INTRA_ALGORITHM
             MPICH_ISCAN_INTRA_ALGORITHM
    Description: Variable to select allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_smp                  - Force smp algorithm
        sched_recursive_doubling   - Force recursive doubling algorithm
        gentran_recursive_doubling - Force generic transport recursive
        doubling algorithm
    Default: MPIR_CVAR_ISCAN_INTRA_ALGORITHM_auto

MPIR_CVAR_ISCAN_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ISCAN_DEVICE_COLLECTIVE
             MPICH_ISCAN_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iscan will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ISCATTER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ISCATTER_INTRA_ALGORITHM
             MPICH_ISCATTER_INTRA_ALGORITHM
    Description: Variable to select iscatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_binomial     - Force binomial algorithm
        gentran_tree       - Force genetric transport based tree algorithm
    Default: MPIR_CVAR_ISCATTER_INTRA_ALGORITHM_auto

MPIR_CVAR_ISCATTER_TREE_KVAL
    Aliases: MPIR_PARAM_ISCATTER_TREE_KVAL
             MPICH_ISCATTER_TREE_KVAL
    Description: k value for tree based iscatter
    Default: 2

MPIR_CVAR_ISCATTER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ISCATTER_INTER_ALGORITHM
             MPICH_ISCATTER_INTER_ALGORITHM
    Description: Variable to select iscatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear                    - Force linear algorithm
        sched_remote_send_local_scatter - Force remote-send-local-scatter
        algorithm
    Default: MPIR_CVAR_ISCATTER_INTER_ALGORITHM_auto

MPIR_CVAR_ISCATTER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ISCATTER_DEVICE_COLLECTIVE
             MPICH_ISCATTER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iscatter will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_ISCATTERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ISCATTERV_INTRA_ALGORITHM
             MPICH_ISCATTERV_INTRA_ALGORITHM
    Description: Variable to select iscatterv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear    - Force linear algorithm
        gentran_linear  - Force generic transport based linear algorithm
    Default: MPIR_CVAR_ISCATTERV_INTRA_ALGORITHM_auto

MPIR_CVAR_ISCATTERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_ISCATTERV_INTER_ALGORITHM
             MPICH_ISCATTERV_INTER_ALGORITHM
    Description: Variable to select iscatterv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        sched_auto - Internal algorithm selection for sched-based
        algorithms
        sched_linear - Force linear algorithm
    Default: MPIR_CVAR_ISCATTERV_INTER_ALGORITHM_auto

MPIR_CVAR_ISCATTERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_ISCATTERV_DEVICE_COLLECTIVE
             MPICH_ISCATTERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Iscatterv will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_NEIGHBOR_ALLGATHER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLGATHER_INTRA_ALGORITHM
             MPICH_NEIGHBOR_ALLGATHER_INTRA_ALGORITHM
    Description: Variable to select ineighbor_allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nonblocking algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLGATHER_INTRA_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLGATHER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLGATHER_INTER_ALGORITHM
             MPICH_NEIGHBOR_ALLGATHER_INTER_ALGORITHM
    Description: Variable to select ineighbor_allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nonblocking algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLGATHER_INTER_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLGATHER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_NEIGHBOR_ALLGATHER_DEVICE_COLLECTIVE
             MPICH_NEIGHBOR_ALLGATHER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Neighbor_allgather will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_NEIGHBOR_ALLGATHERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLGATHERV_INTRA_ALGORITHM
             MPICH_NEIGHBOR_ALLGATHERV_INTRA_ALGORITHM
    Description: Variable to select neighbor_allgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLGATHERV_INTRA_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLGATHERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLGATHERV_INTER_ALGORITHM
             MPICH_NEIGHBOR_ALLGATHERV_INTER_ALGORITHM
    Description: Variable to select neighbor_allgatherv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLGATHERV_INTER_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLGATHERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_NEIGHBOR_ALLGATHERV_DEVICE_COLLECTIVE
             MPICH_NEIGHBOR_ALLGATHERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Neighbor_allgatherv will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_NEIGHBOR_ALLTOALL_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALL_INTRA_ALGORITHM
             MPICH_NEIGHBOR_ALLTOALL_INTRA_ALGORITHM
    Description: Variable to select neighbor_alltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLTOALL_INTRA_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLTOALL_INTER_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALL_INTER_ALGORITHM
             MPICH_NEIGHBOR_ALLTOALL_INTER_ALGORITHM
    Description: Variable to select neighbor_alltoall algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLTOALL_INTER_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLTOALL_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALL_DEVICE_COLLECTIVE
             MPICH_NEIGHBOR_ALLTOALL_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Neighbor_alltoall will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_NEIGHBOR_ALLTOALLV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALLV_INTRA_ALGORITHM
             MPICH_NEIGHBOR_ALLTOALLV_INTRA_ALGORITHM
    Description: Variable to select neighbor_alltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLTOALLV_INTRA_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLTOALLV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALLV_INTER_ALGORITHM
             MPICH_NEIGHBOR_ALLTOALLV_INTER_ALGORITHM
    Description: Variable to select neighbor_alltoallv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLTOALLV_INTER_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLTOALLV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALLV_DEVICE_COLLECTIVE
             MPICH_NEIGHBOR_ALLTOALLV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Neighbor_alltoallv will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_NEIGHBOR_ALLTOALLW_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALLW_INTRA_ALGORITHM
             MPICH_NEIGHBOR_ALLTOALLW_INTRA_ALGORITHM
    Description: Variable to select neighbor_alltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLTOALLW_INTRA_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLTOALLW_INTER_ALGORITHM
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALLW_INTER_ALGORITHM
             MPICH_NEIGHBOR_ALLTOALLW_INTER_ALGORITHM
    Description: Variable to select neighbor_alltoallw algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb   - Force nb algorithm
    Default: MPIR_CVAR_NEIGHBOR_ALLTOALLW_INTER_ALGORITHM_auto

MPIR_CVAR_NEIGHBOR_ALLTOALLW_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_NEIGHBOR_ALLTOALLW_DEVICE_COLLECTIVE
             MPICH_NEIGHBOR_ALLTOALLW_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Neighbor_alltoallw will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_REDUCE_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_REDUCE_SHORT_MSG_SIZE
             MPICH_REDUCE_SHORT_MSG_SIZE
    Description: the short message algorithm will be used if the send
        buffer size is <= this value (in bytes)
    Default: 2048

MPIR_CVAR_MAX_SMP_REDUCE_MSG_SIZE
    Aliases: MPIR_PARAM_MAX_SMP_REDUCE_MSG_SIZE
             MPICH_MAX_SMP_REDUCE_MSG_SIZE
    Description: Maximum message size for which SMP-aware reduce is used. 
        A value of '0' uses SMP-aware reduce for all message sizes.
    Default: 0

MPIR_CVAR_REDUCE_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_REDUCE_INTRA_ALGORITHM
             MPICH_REDUCE_INTRA_ALGORITHM
    Description: Variable to select reduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        binomial              - Force binomial algorithm
        nb                    - Force nonblocking algorithm
        smp                   - Force smp algorithm
        reduce_scatter_gather - Force reduce scatter gather algorithm
    Default: MPIR_CVAR_REDUCE_INTRA_ALGORITHM_auto

MPIR_CVAR_REDUCE_INTER_ALGORITHM
    Aliases: MPIR_PARAM_REDUCE_INTER_ALGORITHM
             MPICH_REDUCE_INTER_ALGORITHM
    Description: Variable to select reduce algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        local_reduce_remote_send - Force local-reduce-remote-send algorithm
        nb                       - Force nonblocking algorithm
    Default: MPIR_CVAR_REDUCE_INTER_ALGORITHM_auto

MPIR_CVAR_REDUCE_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_REDUCE_DEVICE_COLLECTIVE
             MPICH_REDUCE_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Reduce will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_REDUCE_SCATTER_COMMUTATIVE_LONG_MSG_SIZE
    Aliases: MPIR_PARAM_REDUCE_SCATTER_COMMUTATIVE_LONG_MSG_SIZE
             MPICH_REDUCE_SCATTER_COMMUTATIVE_LONG_MSG_SIZE
    Description: the long message algorithm will be used if the operation
        is commutative and the send buffer size is >= this value (in bytes)
    Default: 524288

MPIR_CVAR_REDUCE_SCATTER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_REDUCE_SCATTER_INTRA_ALGORITHM
             MPICH_REDUCE_SCATTER_INTRA_ALGORITHM
    Description: Variable to select reduce_scatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                 - Force nonblocking algorithm
        noncommutative     - Force noncommutative algorithm
        pairwise           - Force pairwise algorithm
        recursive_doubling - Force recursive doubling algorithm
        recursive_halving  - Force recursive halving algorithm
    Default: MPIR_CVAR_REDUCE_SCATTER_INTRA_ALGORITHM_auto

MPIR_CVAR_REDUCE_SCATTER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_REDUCE_SCATTER_INTER_ALGORITHM
             MPICH_REDUCE_SCATTER_INTER_ALGORITHM
    Description: Variable to select reduce_scatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                          - Force nonblocking algorithm
        remote_reduce_local_scatter - Force remote-reduce-local-scatter
        algorithm
    Default: MPIR_CVAR_REDUCE_SCATTER_INTER_ALGORITHM_auto

MPIR_CVAR_REDUCE_SCATTER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_REDUCE_SCATTER_DEVICE_COLLECTIVE
             MPICH_REDUCE_SCATTER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Reduce_scatter will allow
        the device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_REDUCE_SCATTER_BLOCK_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_REDUCE_SCATTER_BLOCK_INTRA_ALGORITHM
             MPICH_REDUCE_SCATTER_BLOCK_INTRA_ALGORITHM
    Description: Variable to select reduce_scatter_block algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        noncommutative     - Force noncommutative algorithm
        recursive_doubling - Force recursive doubling algorithm
        pairwise           - Force pairwise algorithm
        recursive_halving  - Force recursive halving algorithm
        nb                 - Force nonblocking algorithm
    Default: MPIR_CVAR_REDUCE_SCATTER_BLOCK_INTRA_ALGORITHM_auto

MPIR_CVAR_REDUCE_SCATTER_BLOCK_INTER_ALGORITHM
    Aliases: MPIR_PARAM_REDUCE_SCATTER_BLOCK_INTER_ALGORITHM
             MPICH_REDUCE_SCATTER_BLOCK_INTER_ALGORITHM
    Description: Variable to select reduce_scatter_block algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                          - Force nonblocking algorithm
        remote_reduce_local_scatter - Force remote-reduce-local-scatter
        algorithm
    Default: MPIR_CVAR_REDUCE_SCATTER_BLOCK_INTER_ALGORITHM_auto

MPIR_CVAR_REDUCE_SCATTER_BLOCK_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_REDUCE_SCATTER_BLOCK_DEVICE_COLLECTIVE
             MPICH_REDUCE_SCATTER_BLOCK_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Reduce_scatter_block will
        allow the device to override the MPIR-level collective algorithms. 
        The device might still call the MPIR-level algorithms manually.  If
        set to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_SCAN_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_SCAN_INTRA_ALGORITHM
             MPICH_SCAN_INTRA_ALGORITHM
    Description: Variable to select allgather algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        nb                 - Force nonblocking algorithm
        smp                - Force smp algorithm
        recursive_doubling - Force recursive doubling algorithm
    Default: MPIR_CVAR_SCAN_INTRA_ALGORITHM_auto

MPIR_CVAR_SCAN_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_SCAN_DEVICE_COLLECTIVE
             MPICH_SCAN_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Scan will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_SCATTER_INTER_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_SCATTER_INTER_SHORT_MSG_SIZE
             MPICH_SCATTER_INTER_SHORT_MSG_SIZE
    Description: use the short message algorithm for intercommunicator
        MPI_Scatter if the send buffer size is < this value (in bytes)
    Default: 2048

MPIR_CVAR_SCATTER_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_SCATTER_INTRA_ALGORITHM
             MPICH_SCATTER_INTRA_ALGORITHM
    Description: Variable to select scatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        binomial - Force binomial algorithm
        nb       - Force nonblocking algorithm
    Default: MPIR_CVAR_SCATTER_INTRA_ALGORITHM_auto

MPIR_CVAR_SCATTER_INTER_ALGORITHM
    Aliases: MPIR_PARAM_SCATTER_INTER_ALGORITHM
             MPICH_SCATTER_INTER_ALGORITHM
    Description: Variable to select scatter algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        linear                    - Force linear algorithm
        nb                        - Force nonblocking algorithm
        remote_send_local_scatter - Force remote-send-local-scatter
        algorithm
    Default: MPIR_CVAR_SCATTER_INTER_ALGORITHM_auto

MPIR_CVAR_SCATTER_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_SCATTER_DEVICE_COLLECTIVE
             MPICH_SCATTER_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Scatter will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_SCATTERV_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_SCATTERV_INTRA_ALGORITHM
             MPICH_SCATTERV_INTRA_ALGORITHM
    Description: Variable to select scatterv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        linear - Force linear algorithm
        nb     - Force nonblocking algorithm
    Default: MPIR_CVAR_SCATTERV_INTRA_ALGORITHM_auto

MPIR_CVAR_SCATTERV_INTER_ALGORITHM
    Aliases: MPIR_PARAM_SCATTERV_INTER_ALGORITHM
             MPICH_SCATTERV_INTER_ALGORITHM
    Description: Variable to select scatterv algorithm
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE)
        linear - Force linear algorithm
        nb     - Force nonblocking algorithm
    Default: MPIR_CVAR_SCATTERV_INTER_ALGORITHM_auto

MPIR_CVAR_SCATTERV_DEVICE_COLLECTIVE
    Aliases: MPIR_PARAM_SCATTERV_DEVICE_COLLECTIVE
             MPICH_SCATTERV_DEVICE_COLLECTIVE
    Description: This CVAR is only used when MPIR_CVAR_DEVICE_COLLECTIVES
        is set to "percoll".  If set to true, MPI_Scatterv will allow the
        device to override the MPIR-level collective algorithms.  The
        device might still call the MPIR-level algorithms manually.  If set
        to false, the device-override will be disabled.
    Default: 1

MPIR_CVAR_DEVICE_COLLECTIVES
    Aliases: MPIR_PARAM_DEVICE_COLLECTIVES
             MPICH_DEVICE_COLLECTIVES
    Description: Variable to select whether the device can override the
        MPIR-level collective algorithms.
        all     - Always prefer the device collectives
        none    - Never pick the device collectives
        percoll - Use the per-collective CVARs to decide
    Default: MPIR_CVAR_DEVICE_COLLECTIVES_percoll

MPIR_CVAR_COLLECTIVE_FALLBACK
    Aliases: MPIR_PARAM_COLLECTIVE_FALLBACK
             MPICH_COLLECTIVE_FALLBACK
    Description: Variable to control what the MPI library should do if the
        user-specified collective algorithm does not work for the
        arguments passed in by the user.
        error   - throw an error
        print   - print an error message and fallback to the internally
        selected algorithm
        silent  - silently fallback to the internally selected algorithm
    Default: MPIR_CVAR_COLLECTIVE_FALLBACK_error

MPIR_CVAR_COLL_SELECTION_TUNING_JSON_FILE
    Aliases: MPIR_PARAM_COLL_SELECTION_TUNING_JSON_FILE
             MPICH_COLL_SELECTION_TUNING_JSON_FILE
    Description: Defines the location of tuning file.
    Default: ""

MPIR_CVAR_PROGRESS_MAX_COLLS
    Aliases: MPIR_PARAM_PROGRESS_MAX_COLLS
             MPICH_PROGRESS_MAX_COLLS
    Description: Maximum number of collective operations at a time that the
        progress engine should make progress on
    Default: 8

MPIR_CVAR_COMM_SPLIT_USE_QSORT
    Aliases: MPIR_PARAM_COMM_SPLIT_USE_QSORT
             MPICH_COMM_SPLIT_USE_QSORT
    Description: Use qsort(3) in the implementation of MPI_Comm_split
        instead of bubble sort.
    Default: 1

MPIR_CVAR_CTXID_EAGER_SIZE
    Aliases: MPIR_PARAM_CTXID_EAGER_SIZE
             MPICH_CTXID_EAGER_SIZE
    Description: The MPIR_CVAR_CTXID_EAGER_SIZE environment variable allows
        you to specify how many words in the context ID mask will be set
        aside for the eager allocation protocol.  If the application is
        running out of context IDs, reducing this value may help.
    Default: 2

MPIR_CVAR_DATALOOP_FAST_SEEK
    Aliases: MPIR_PARAM_DATALOOP_FAST_SEEK
             MPICH_DATALOOP_FAST_SEEK
    Description: use a datatype-specialized algorithm to shortcut seeking
        to the correct location in a noncontiguous buffer
    Default: 1

MPIR_CVAR_PROCTABLE_SIZE
    Aliases: MPIR_PARAM_PROCTABLE_SIZE
             MPICH_PROCTABLE_SIZE
    Description: Size of the "MPIR" debugger interface proctable (process
        table).
    Default: 64

MPIR_CVAR_PROCTABLE_PRINT
    Aliases: MPIR_PARAM_PROCTABLE_PRINT
             MPICH_PROCTABLE_PRINT
    Description: If true, dump the proctable entries at
        MPII_Wait_for_debugger-time.
    Default: 0

MPIR_CVAR_PRINT_ERROR_STACK
    Aliases: MPIR_PARAM_PRINT_ERROR_STACK
             MPICH_PRINT_ERROR_STACK
    Description: If true, print an error stack trace at error handling
        time.
    Default: 1

MPIR_CVAR_CHOP_ERROR_STACK
    Aliases: MPIR_PARAM_CHOP_ERROR_STACK
             MPICH_CHOP_ERROR_STACK
    Description: If >0, truncate error stack output lines this many
        characters wide.  If 0, do not truncate, and if <0 use a sensible
        default.
    Default: 0

MPIR_CVAR_SUPPRESS_ABORT_MESSAGE
    Aliases: MPIR_PARAM_SUPPRESS_ABORT_MESSAGE
             MPICH_SUPPRESS_ABORT_MESSAGE
    Description: Disable printing of abort error message.
    Default: 0

MPIR_CVAR_DEFAULT_THREAD_LEVEL
    Aliases: MPIR_PARAM_DEFAULT_THREAD_LEVEL
             MPICH_DEFAULT_THREAD_LEVEL
    Description: Sets the default thread level to use when using MPI_INIT.
        This variable is case-insensitive.
    Default: "MPI_THREAD_SINGLE"

MPIR_CVAR_ASYNC_PROGRESS
    Aliases: MPIR_PARAM_ASYNC_PROGRESS
             MPICH_ASYNC_PROGRESS
    Description: If set to true, MPICH will initiate an additional thread
        to make asynchronous progress on all communication operations
        including point-to-point, collective, one-sided operations and I/O.
         Setting this variable will automatically increase the
        thread-safety level to MPI_THREAD_MULTIPLE.  While this improves
        the progress semantics, it might cause a small amount of
        performance overhead for regular MPI operations.  The user is
        encouraged to leave one or more hardware threads vacant in order to
        prevent contention between the application threads and the progress
        thread(s).  The impact of oversubscription is highly system
        dependent but may be substantial in some cases, hence this
        recommendation.
    Default: 0

MPIR_CVAR_DEBUG_HOLD
    Aliases: MPIR_PARAM_DEBUG_HOLD
             MPICH_DEBUG_HOLD
    Description: If true, causes processes to wait in MPI_Init and
        MPI_Initthread for a debugger to be attached.  Once the debugger
        has attached, the variable 'hold' should be set to 0 in order to
        allow the process to continue (e.g., in gdb, "set hold=0").
    Default: 0

MPIR_CVAR_ERROR_CHECKING
    Aliases: MPIR_PARAM_ERROR_CHECKING
             MPICH_ERROR_CHECKING
    Description: If true, perform checks for errors, typically to verify
        valid inputs to MPI routines.  Only effective when MPICH is
        configured with --enable-error-checking=runtime .
    Default: 1

MPIR_CVAR_MEMDUMP
    Aliases: MPIR_PARAM_MEMDUMP
             MPICH_MEMDUMP
    Description: If true, list any memory that was allocated by MPICH and
        that remains allocated when MPI_Finalize completes.
    Default: 1

MPIR_CVAR_MEM_CATEGORY_INFORMATION
    Aliases: MPIR_PARAM_MEM_CATEGORY_INFORMATION
             MPICH_MEM_CATEGORY_INFORMATION
    Description: If true, print a summary of memory allocation by category.
        The category definitions are found in mpl_trmem.h.
    Default: 0

MPIR_CVAR_DIMS_VERBOSE
    Aliases: MPIR_PARAM_DIMS_VERBOSE
             MPICH_DIMS_VERBOSE
    Description: If true, enable verbose output about the actions of the
        implementation of MPI_Dims_create.
    Default: 0

MPIR_CVAR_NAMESERV_FILE_PUBDIR
    Aliases: MPIR_PARAM_NAMESERV_FILE_PUBDIR
             MPICH_NAMESERV_FILE_PUBDIR
             MPIR_CVAR_NAMEPUB_DIR
             MPIR_PARAM_NAMEPUB_DIR
             MPICH_NAMEPUB_DIR
    Description: Sets the directory to use for MPI service publishing in
        the file nameserv implementation.  Allows the user to override
        where the publish and lookup information is placed for
        connect/accept based applications.
    Default: NULL

MPIR_CVAR_ABORT_ON_LEAKED_HANDLES
    Aliases: MPIR_PARAM_ABORT_ON_LEAKED_HANDLES
             MPICH_ABORT_ON_LEAKED_HANDLES
    Description: If true, MPI will call MPI_Abort at MPI_Finalize if any
        MPI object handles have been leaked.  For example, if MPI_Comm_dup
        is called without calling a corresponding MPI_Comm_free.  For
        uninteresting reasons, enabling this option may prevent all known
        object leaks from being reported.  MPICH must have been configure
        with "--enable-g=handlealloc" or better in order for this
        functionality to work.
    Default: 0

MPIR_CVAR_NETLOC_NODE_FILE
    Aliases: MPIR_PARAM_NETLOC_NODE_FILE
             MPICH_NETLOC_NODE_FILE
    Description: Subnet json file
    Default: "auto"

MPIR_CVAR_NOLOCAL
    Aliases: MPIR_PARAM_NOLOCAL
             MPICH_NOLOCAL
             MPIR_CVAR_NO_LOCAL
             MPIR_PARAM_NO_LOCAL
             MPICH_NO_LOCAL
    Description: If true, force all processes to operate as though all
        processes are located on another node.  For example, this disables
        shared memory communication hierarchical collectives.
    Default: 0

MPIR_CVAR_ODD_EVEN_CLIQUES
    Aliases: MPIR_PARAM_ODD_EVEN_CLIQUES
             MPICH_ODD_EVEN_CLIQUES
             MPIR_CVAR_EVEN_ODD_CLIQUES
             MPIR_PARAM_EVEN_ODD_CLIQUES
             MPICH_EVEN_ODD_CLIQUES
    Description: If true, odd procs on a node are seen as local to each
        other, and even procs on a node are seen as local to each other. 
        Used for debugging on a single machine. Deprecated in favor of
        MPIR_CVAR_NUM_CLIQUES.
    Default: 0

MPIR_CVAR_NUM_CLIQUES
    Aliases: MPIR_PARAM_NUM_CLIQUES
             MPICH_NUM_CLIQUES
             MPIR_CVAR_NUM_CLIQUES
             MPIR_PARAM_NUM_CLIQUES
             MPICH_NUM_CLIQUES
    Description: Specify the number of cliques that should be used to
        partition procs on a local node. Procs with the same clique number
        are seen as local to each other. Used for debugging on a single
        machine.
    Default: 1

MPIR_CVAR_COLL_ALIAS_CHECK
    Aliases: MPIR_PARAM_COLL_ALIAS_CHECK
             MPICH_COLL_ALIAS_CHECK
    Description: Enable checking of aliasing in collective operations
    Default: 1

MPIR_CVAR_ENABLE_GPU
    Aliases: MPIR_PARAM_ENABLE_GPU
             MPICH_ENABLE_GPU
    Description: Control MPICH GPU support. If set to 0, all GPU support is
        disabled and we do not query the buffer type internally because we
        assume no GPU buffer is use.
    Default: 1

MPIR_CVAR_REQUEST_POLL_FREQ
    Aliases: MPIR_PARAM_REQUEST_POLL_FREQ
             MPICH_REQUEST_POLL_FREQ
    Description: How frequent to poll during completion calls (wait/test)
        in terms of number of processed requests before polling.
    Default: 8

MPIR_CVAR_REQUEST_BATCH_SIZE
    Aliases: MPIR_PARAM_REQUEST_BATCH_SIZE
             MPICH_REQUEST_BATCH_SIZE
    Description: The number of requests to make completion as a batch in
        MPI_Waitall and MPI_Testall implementation. A large number is
        likely to cause more cache misses.
    Default: 64

MPIR_CVAR_POLLS_BEFORE_YIELD
    Aliases: MPIR_PARAM_POLLS_BEFORE_YIELD
             MPICH_POLLS_BEFORE_YIELD
    Description: When MPICH is in a busy waiting loop, it will periodically
        call a function to yield the processor.  This cvar sets the number
        of loops before the yield function is called.  A value of 0
        disables yielding.
    Default: 1000

MPIR_CVAR_OFI_USE_PROVIDER
    Aliases: MPIR_PARAM_OFI_USE_PROVIDER
             MPICH_OFI_USE_PROVIDER
    Description: If non-null, choose an OFI provider by name. If using with
        the CH4 device and using an older libfabric installation than the
        recommended version to accompany this MPICH version, unexpected
        results may occur.
    Default: NULL

MPIR_CVAR_CH3_INTERFACE_HOSTNAME
    Aliases: MPIR_PARAM_CH3_INTERFACE_HOSTNAME
             MPICH_CH3_INTERFACE_HOSTNAME
             MPIR_CVAR_INTERFACE_HOSTNAME
             MPIR_PARAM_INTERFACE_HOSTNAME
             MPICH_INTERFACE_HOSTNAME
    Description: If non-NULL, this cvar specifies the IP address that other
        processes should use when connecting to this process. This cvar is
        mutually exclusive with the MPIR_CVAR_CH3_NETWORK_IFACE cvar and it
        is an error to set them both.
    Default: NULL

MPIR_CVAR_CH3_PORT_RANGE
    Aliases: MPIR_PARAM_CH3_PORT_RANGE
             MPICH_CH3_PORT_RANGE
             MPIR_CVAR_PORTRANGE
             MPIR_CVAR_PORT_RANGE
             MPIR_PARAM_PORTRANGE
             MPIR_PARAM_PORT_RANGE
             MPICH_PORTRANGE
             MPICH_PORT_RANGE
    Description: The MPIR_CVAR_CH3_PORT_RANGE environment variable allows
        you to specify the range of TCP ports to be used by the process
        manager and the MPICH library. The format of this variable is
        <low>:<high>.  To specify any available port, use 0:0.
    Default: {0,0}

MPIR_CVAR_NEMESIS_TCP_NETWORK_IFACE
    Aliases: MPIR_PARAM_NEMESIS_TCP_NETWORK_IFACE
             MPICH_NEMESIS_TCP_NETWORK_IFACE
             MPIR_CVAR_NETWORK_IFACE
             MPIR_PARAM_NETWORK_IFACE
             MPICH_NETWORK_IFACE
    Description: If non-NULL, this cvar specifies which pseudo-ethernet
        interface the tcp netmod should use (e.g., "eth1", "ib0"). Note,
        this is a Linux-specific cvar. This cvar is mutually exclusive with
        the MPIR_CVAR_CH3_INTERFACE_HOSTNAME cvar and it is an error to set
        them both.
    Default: NULL

MPIR_CVAR_NEMESIS_TCP_HOST_LOOKUP_RETRIES
    Aliases: MPIR_PARAM_NEMESIS_TCP_HOST_LOOKUP_RETRIES
             MPICH_NEMESIS_TCP_HOST_LOOKUP_RETRIES
    Description: This cvar controls the number of times to retry the
        gethostbyname() function before giving up.
    Default: 10

MPIR_CVAR_NEMESIS_ENABLE_CKPOINT
    Aliases: MPIR_PARAM_NEMESIS_ENABLE_CKPOINT
             MPICH_NEMESIS_ENABLE_CKPOINT
    Description: If true, enables checkpointing support and returns an
        error if checkpointing library cannot be initialized.
    Default: 0

MPIR_CVAR_NEMESIS_SHM_EAGER_MAX_SZ
    Aliases: MPIR_PARAM_NEMESIS_SHM_EAGER_MAX_SZ
             MPICH_NEMESIS_SHM_EAGER_MAX_SZ
    Description: This cvar controls the message size at which Nemesis
        switches from eager to rendezvous mode for shared memory. If this
        cvar is set to -1, then Nemesis will choose an appropriate value.
    Default: -1

MPIR_CVAR_NEMESIS_SHM_READY_EAGER_MAX_SZ
    Aliases: MPIR_PARAM_NEMESIS_SHM_READY_EAGER_MAX_SZ
             MPICH_NEMESIS_SHM_READY_EAGER_MAX_SZ
    Description: This cvar controls the message size at which Nemesis
        switches from eager to rendezvous mode for ready-send messages.  If
        this cvar is set to -1, then ready messages will always be sent
        eagerly.  If this cvar is set to -2, then Nemesis will choose an
        appropriate value.
    Default: -2

MPIR_CVAR_ENABLE_FT
    Aliases: MPIR_PARAM_ENABLE_FT
             MPICH_ENABLE_FT
    Description: Enable fault tolerance functions
    Default: 0

MPIR_CVAR_NEMESIS_NETMOD
    Aliases: MPIR_PARAM_NEMESIS_NETMOD
             MPICH_NEMESIS_NETMOD
    Description: If non-empty, this cvar specifies which network module
        should be used for communication. This variable is
        case-insensitive.
    Default: ""

MPIR_CVAR_CH3_ENABLE_HCOLL
    Aliases: MPIR_PARAM_CH3_ENABLE_HCOLL
             MPICH_CH3_ENABLE_HCOLL
    Description: If true, enable HCOLL collectives.
    Default: 0

MPIR_CVAR_CH3_COMM_CONNECT_TIMEOUT
    Aliases: MPIR_PARAM_CH3_COMM_CONNECT_TIMEOUT
             MPICH_CH3_COMM_CONNECT_TIMEOUT
    Description: The default time out period in seconds for a connection
        attempt to the server communicator where the named port exists but
        no pending accept. User can change the value for a specified
        connection through its info argument.
    Default: 180

MPIR_CVAR_CH3_RMA_OP_PIGGYBACK_LOCK_DATA_SIZE
    Aliases: MPIR_PARAM_CH3_RMA_OP_PIGGYBACK_LOCK_DATA_SIZE
             MPICH_CH3_RMA_OP_PIGGYBACK_LOCK_DATA_SIZE
    Description: Specify the threshold of data size of a RMA operation
        which can be piggybacked with a LOCK message. It is always a
        positive value and should not be smaller than
        MPIDI_RMA_IMMED_BYTES. If user sets it as a small value, for middle
        and large data size, we will lose performance because of always
        waiting for round-trip of LOCK synchronization; if user sets it as
        a large value, we need to consume more memory on target side to
        buffer this lock request when lock is not satisfied.
    Default: 65536

MPIR_CVAR_CH3_RMA_ACTIVE_REQ_THRESHOLD
    Aliases: MPIR_PARAM_CH3_RMA_ACTIVE_REQ_THRESHOLD
             MPICH_CH3_RMA_ACTIVE_REQ_THRESHOLD
    Description: Threshold of number of active requests to trigger blocking
        waiting in operation routines. When the value is negative, we never
        blockingly wait in operation routines. When the value is zero, we
        always trigger blocking waiting in operation routines to wait until
        no. of active requests becomes zero. When the value is positive, we
        do blocking waiting in operation routines to wait until no. of
        active requests being reduced to this value.
    Default: 65536

MPIR_CVAR_CH3_RMA_POKE_PROGRESS_REQ_THRESHOLD
    Aliases: MPIR_PARAM_CH3_RMA_POKE_PROGRESS_REQ_THRESHOLD
             MPICH_CH3_RMA_POKE_PROGRESS_REQ_THRESHOLD
    Description: Threshold at which the RMA implementation attempts to
        complete requests while completing RMA operations and while using
        the lazy synchonization approach.  Change this value if programs
        fail because they run out of requests or other internal resources
    Default: 128

MPIR_CVAR_CH3_RMA_SCALABLE_FENCE_PROCESS_NUM
    Aliases: MPIR_PARAM_CH3_RMA_SCALABLE_FENCE_PROCESS_NUM
             MPICH_CH3_RMA_SCALABLE_FENCE_PROCESS_NUM
    Description: Specify the threshold of switching the algorithm used in
        FENCE from the basic algorithm to the scalable algorithm. The value
        can be nagative, zero or positive. When the number of processes is
        larger than or equal to this value, FENCE will use a scalable
        algorithm which do not use O(P) data structure; when the number of
        processes is smaller than the value, FENCE will use a basic but
        fast algorithm which requires an O(P) data structure.
    Default: 1024

MPIR_CVAR_CH3_RMA_DELAY_ISSUING_FOR_PIGGYBACKING
    Aliases: MPIR_PARAM_CH3_RMA_DELAY_ISSUING_FOR_PIGGYBACKING
             MPICH_CH3_RMA_DELAY_ISSUING_FOR_PIGGYBACKING
    Description: Specify if delay issuing of RMA operations for
        piggybacking LOCK/UNLOCK/FLUSH is enabled. It can be either 0 or 1.
        When it is set to 1, the issuing of LOCK message is delayed until
        origin process see the first RMA operation and piggyback LOCK with
        that operation, and the origin process always keeps the current
        last operation until the ending synchronization call in order to
        piggyback UNLOCK/FLUSH with that operation. When it is set to 0, in
        WIN_LOCK/UNLOCK case, the LOCK message is sent out as early as
        possible, in WIN_LOCK_ALL/UNLOCK_ALL case, the origin process still
        tries to piggyback LOCK message with the first operation; for
        UNLOCK/FLUSH message, the origin process no longer keeps the
        current last operation but only piggyback UNLOCK/FLUSH if there is
        an operation avaliable in the ending synchronization call.
    Default: 0

MPIR_CVAR_CH3_RMA_SLOTS_SIZE
    Aliases: MPIR_PARAM_CH3_RMA_SLOTS_SIZE
             MPICH_CH3_RMA_SLOTS_SIZE
    Description: Number of RMA slots during window creation. Each slot
        contains a linked list of target elements. The distribution of
        ranks among slots follows a round-robin pattern. Requires a
        positive value.
    Default: 262144

MPIR_CVAR_CH3_RMA_TARGET_LOCK_DATA_BYTES
    Aliases: MPIR_PARAM_CH3_RMA_TARGET_LOCK_DATA_BYTES
             MPICH_CH3_RMA_TARGET_LOCK_DATA_BYTES
    Description: Size (in bytes) of available lock data this window can
        provided. If current buffered lock data is more than this value,
        the process will drop the upcoming operation data. Requires a
        positive calue.
    Default: 655360

MPIR_CVAR_CH3_EAGER_MAX_MSG_SIZE
    Aliases: MPIR_PARAM_CH3_EAGER_MAX_MSG_SIZE
             MPICH_CH3_EAGER_MAX_MSG_SIZE
    Description: This cvar controls the message size at which CH3 switches
        from eager to rendezvous mode.
    Default: 131072

MPIR_CVAR_CH3_PG_VERBOSE
    Aliases: MPIR_PARAM_CH3_PG_VERBOSE
             MPICH_CH3_PG_VERBOSE
    Description: If set, print the PG state on finalize.
    Default: 0

MPIR_CVAR_CH3_RMA_OP_WIN_POOL_SIZE
    Aliases: MPIR_PARAM_CH3_RMA_OP_WIN_POOL_SIZE
             MPICH_CH3_RMA_OP_WIN_POOL_SIZE
    Description: Size of the window-private RMA operations pool (in number
        of operations) that stores information about RMA operations that
        could not be issued immediately.  Requires a positive value.
    Default: 256

MPIR_CVAR_CH3_RMA_OP_GLOBAL_POOL_SIZE
    Aliases: MPIR_PARAM_CH3_RMA_OP_GLOBAL_POOL_SIZE
             MPICH_CH3_RMA_OP_GLOBAL_POOL_SIZE
    Description: Size of the Global RMA operations pool (in number of
        operations) that stores information about RMA operations that could
        not be issued immediatly.  Requires a positive value.
    Default: 16384

MPIR_CVAR_CH3_RMA_TARGET_WIN_POOL_SIZE
    Aliases: MPIR_PARAM_CH3_RMA_TARGET_WIN_POOL_SIZE
             MPICH_CH3_RMA_TARGET_WIN_POOL_SIZE
    Description: Size of the window-private RMA target pool (in number of
        targets) that stores information about RMA targets that could not
        be issued immediately.  Requires a positive value.
    Default: 256

MPIR_CVAR_CH3_RMA_TARGET_GLOBAL_POOL_SIZE
    Aliases: MPIR_PARAM_CH3_RMA_TARGET_GLOBAL_POOL_SIZE
             MPICH_CH3_RMA_TARGET_GLOBAL_POOL_SIZE
    Description: Size of the Global RMA targets pool (in number of targets)
        that stores information about RMA targets that could not be issued
        immediatly.  Requires a positive value.
    Default: 16384

MPIR_CVAR_CH3_RMA_TARGET_LOCK_ENTRY_WIN_POOL_SIZE
    Aliases: MPIR_PARAM_CH3_RMA_TARGET_LOCK_ENTRY_WIN_POOL_SIZE
             MPICH_CH3_RMA_TARGET_LOCK_ENTRY_WIN_POOL_SIZE
    Description: Size of the window-private RMA lock entries pool (in
        number of lock entries) that stores information about RMA lock
        requests that could not be satisfied immediatly.  Requires a
        positive value.
    Default: 256

MPIR_CVAR_CH4_AM_PACK_BUFFER_SIZE
    Aliases: MPIR_PARAM_CH4_AM_PACK_BUFFER_SIZE
             MPICH_CH4_AM_PACK_BUFFER_SIZE
    Description: Specifies the number of buffers for packing/unpacking
        active messages in each block of the pool. The size here should be
        greater or equal to the max of the eager buffer limit of SHM and
        NETMOD.
    Default: 69632

MPIR_CVAR_CH4_NUM_AM_PACK_BUFFERS_PER_CHUNK
    Aliases: MPIR_PARAM_CH4_NUM_AM_PACK_BUFFERS_PER_CHUNK
             MPICH_CH4_NUM_AM_PACK_BUFFERS_PER_CHUNK
    Description: Specifies the number of buffers for packing/unpacking
        active messages in each block of the pool.
    Default: 16

MPIR_CVAR_CH4_MAX_AM_UNEXPECTED_PACK_BUFFERS_SIZE_BYTE
    Aliases: MPIR_PARAM_CH4_MAX_AM_UNEXPECTED_PACK_BUFFERS_SIZE_BYTE
             MPICH_CH4_MAX_AM_UNEXPECTED_PACK_BUFFERS_SIZE_BYTE
    Description: Specifies the max number of buffers for packing/unpacking
        active messages in the pool.
    Default: 8388608

MPIR_CVAR_CH4_OFI_AM_LONG_FORCE_PIPELINE
    Aliases: MPIR_PARAM_CH4_OFI_AM_LONG_FORCE_PIPELINE
             MPICH_CH4_OFI_AM_LONG_FORCE_PIPELINE
    Description: For long message to be sent using pipeline rather than
        default RDMA read.
    Default: 0

MPIR_CVAR_CH4_OFI_CAPABILITY_SETS_DEBUG
    Aliases: MPIR_PARAM_CH4_OFI_CAPABILITY_SETS_DEBUG
             MPICH_CH4_OFI_CAPABILITY_SETS_DEBUG
    Description: Prints out the configuration of each capability selected
        via the capability sets interface.
    Default: 0

MPIR_CVAR_OFI_SKIP_IPV6
    Aliases: MPIR_PARAM_OFI_SKIP_IPV6
             MPICH_OFI_SKIP_IPV6
    Description: Skip IPv6 providers.
    Default: 0

MPIR_CVAR_CH4_OFI_ENABLE_AV_TABLE
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_AV_TABLE
             MPICH_CH4_OFI_ENABLE_AV_TABLE
    Description: If true, the OFI addressing information will be stored
        with an FI_AV_TABLE. If false, an FI_AV_MAP will be used.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_SCALABLE_ENDPOINTS
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_SCALABLE_ENDPOINTS
             MPICH_CH4_OFI_ENABLE_SCALABLE_ENDPOINTS
    Description: If true, use OFI scalable endpoints.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_SHARED_CONTEXTS
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_SHARED_CONTEXTS
             MPICH_CH4_OFI_ENABLE_SHARED_CONTEXTS
    Description: If set to false (zero), MPICH does not use OFI shared
        contexts. If set to -1, it is determined by the OFI capability sets
        based on the provider. Otherwise, MPICH tries to use OFI shared
        contexts. If they are unavailable, it'll fall back to the mode
        without shared contexts.
    Default: 0

MPIR_CVAR_CH4_OFI_ENABLE_MR_SCALABLE
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_MR_SCALABLE
             MPICH_CH4_OFI_ENABLE_MR_SCALABLE
    Description: This variable is only provided for backward compatibility.
        When using OFI versions 1.5+, use the other memory region
        variables. If true, MR_SCALABLE for OFI memory regions. If false,
        MR_BASIC for OFI memory regions.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_MR_VIRT_ADDRESS
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_MR_VIRT_ADDRESS
             MPICH_CH4_OFI_ENABLE_MR_VIRT_ADDRESS
    Description: If true, enable virtual addressing for OFI memory regions.
        This variable is only meaningful for OFI versions 1.5+. It is
        equivelent to using FI_MR_BASIC in versions of OFI older than 1.5.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_MR_ALLOCATED
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_MR_ALLOCATED
             MPICH_CH4_OFI_ENABLE_MR_ALLOCATED
    Description: If true, require all OFI memory regions must be backed by
        physical memory pages at the time the registration call is made.
        This variable is only meaningful for OFI versions 1.5+. It is
        equivelent to using FI_MR_BASIC in versions of OFI older than 1.5.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_MR_PROV_KEY
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_MR_PROV_KEY
             MPICH_CH4_OFI_ENABLE_MR_PROV_KEY
    Description: If true, enable provider supplied key for OFI memory
        regions. This variable is only meaningful for OFI versions 1.5+. It
        is equivelent to using FI_MR_BASIC in versions of OFI older than
        1.5.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_TAGGED
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_TAGGED
             MPICH_CH4_OFI_ENABLE_TAGGED
    Description: If true, use tagged message transmission functions in OFI.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_AM
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_AM
             MPICH_CH4_OFI_ENABLE_AM
    Description: If true, enable OFI active message support.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_RMA
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_RMA
             MPICH_CH4_OFI_ENABLE_RMA
    Description: If true, enable OFI RMA support for MPI RMA operations.
        OFI support for basic RMA is always required to implement large
        messgage transfers in the active message code path.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_ATOMICS
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_ATOMICS
             MPICH_CH4_OFI_ENABLE_ATOMICS
    Description: If true, enable OFI Atomics support.
    Default: -1

MPIR_CVAR_CH4_OFI_FETCH_ATOMIC_IOVECS
    Aliases: MPIR_PARAM_CH4_OFI_FETCH_ATOMIC_IOVECS
             MPICH_CH4_OFI_FETCH_ATOMIC_IOVECS
    Description: Specifies the maximum number of iovecs that can be used by
        the OFI provider for fetch_atomic operations. The default value is
        -1, indicating that no value is set.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_DATA_AUTO_PROGRESS
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_DATA_AUTO_PROGRESS
             MPICH_CH4_OFI_ENABLE_DATA_AUTO_PROGRESS
    Description: If true, enable MPI data auto progress.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_CONTROL_AUTO_PROGRESS
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_CONTROL_AUTO_PROGRESS
             MPICH_CH4_OFI_ENABLE_CONTROL_AUTO_PROGRESS
    Description: If true, enable MPI control auto progress.
    Default: -1

MPIR_CVAR_CH4_OFI_ENABLE_PT2PT_NOPACK
    Aliases: MPIR_PARAM_CH4_OFI_ENABLE_PT2PT_NOPACK
             MPICH_CH4_OFI_ENABLE_PT2PT_NOPACK
    Description: If true, enable iovec for pt2pt.
    Default: -1

MPIR_CVAR_CH4_OFI_CONTEXT_ID_BITS
    Aliases: MPIR_PARAM_CH4_OFI_CONTEXT_ID_BITS
             MPICH_CH4_OFI_CONTEXT_ID_BITS
    Description: Specifies the number of bits that will be used for
        matching the context ID. The default value is -1, indicating that
        no value is set and that the default will be defined in the
        ofi_types.h file.
    Default: -1

MPIR_CVAR_CH4_OFI_RANK_BITS
    Aliases: MPIR_PARAM_CH4_OFI_RANK_BITS
             MPICH_CH4_OFI_RANK_BITS
    Description: Specifies the number of bits that will be used for
        matching the MPI rank. The default value is -1, indicating that no
        value is set and that the default will be defined in the
        ofi_types.h file.
    Default: -1

MPIR_CVAR_CH4_OFI_TAG_BITS
    Aliases: MPIR_PARAM_CH4_OFI_TAG_BITS
             MPICH_CH4_OFI_TAG_BITS
    Description: Specifies the number of bits that will be used for
        matching the user tag. The default value is -1, indicating that no
        value is set and that the default will be defined in the
        ofi_types.h file.
    Default: -1

MPIR_CVAR_CH4_OFI_MAJOR_VERSION
    Aliases: MPIR_PARAM_CH4_OFI_MAJOR_VERSION
             MPICH_CH4_OFI_MAJOR_VERSION
    Description: Specifies the major version of the OFI library. The
        default is the major version of the OFI library used with MPICH. If
        using this CVAR, it is recommended that the user also specifies a
        specific OFI provider.
    Default: -1

MPIR_CVAR_CH4_OFI_MINOR_VERSION
    Aliases: MPIR_PARAM_CH4_OFI_MINOR_VERSION
             MPICH_CH4_OFI_MINOR_VERSION
    Description: Specifies the major version of the OFI library. The
        default is the minor version of the OFI library used with MPICH. If
        using this CVAR, it is recommended that the user also specifies a
        specific OFI provider.
    Default: -1

MPIR_CVAR_CH4_OFI_MAX_VNIS
    Aliases: MPIR_PARAM_CH4_OFI_MAX_VNIS
             MPICH_CH4_OFI_MAX_VNIS
    Description: If set to positive, this CVAR specifies the maximum number
        of CH4 VNIs that OFI netmod exposes. If set to 0 (the default) or
        bigger than MPIR_CVAR_CH4_NUM_VCIS, the number of exposed VNIs is
        set to MPIR_CVAR_CH4_NUM_VCIS.
    Default: 0

MPIR_CVAR_CH4_OFI_MAX_RMA_SEP_CTX
    Aliases: MPIR_PARAM_CH4_OFI_MAX_RMA_SEP_CTX
             MPICH_CH4_OFI_MAX_RMA_SEP_CTX
    Description: If set to positive, this CVAR specifies the maximum number
        of transmit contexts RMA can utilize in a scalable endpoint. This
        value is effective only when scalable endpoint is available,
        otherwise it will be ignored.
    Default: 0

MPIR_CVAR_CH4_OFI_MAX_EAGAIN_RETRY
    Aliases: MPIR_PARAM_CH4_OFI_MAX_EAGAIN_RETRY
             MPICH_CH4_OFI_MAX_EAGAIN_RETRY
    Description: If set to positive, this CVAR specifies the maximum number
        of retries of an ofi operations before returning MPIX_ERR_EAGAIN.
        This value is effective only when the communicator has the
        MPI_OFI_set_eagain info hint set to true.
    Default: -1

MPIR_CVAR_CH4_OFI_NUM_AM_BUFFERS
    Aliases: MPIR_PARAM_CH4_OFI_NUM_AM_BUFFERS
             MPICH_CH4_OFI_NUM_AM_BUFFERS
    Description: Specifies the number of buffers for receiving active
        messages.
    Default: -1

MPIR_CVAR_CH4_OFI_RMA_PROGRESS_INTERVAL
    Aliases: MPIR_PARAM_CH4_OFI_RMA_PROGRESS_INTERVAL
             MPICH_CH4_OFI_RMA_PROGRESS_INTERVAL
    Description: Specifies the interval for manually flushing RMA
        operations when automatic progress is not enabled. It the
        underlying OFI provider supports auto data progress, this value is
        ignored. If the value is -1, this optimization will be turned off.
    Default: 100

MPIR_CVAR_CH4_OFI_RMA_IOVEC_MAX
    Aliases: MPIR_PARAM_CH4_OFI_RMA_IOVEC_MAX
             MPICH_CH4_OFI_RMA_IOVEC_MAX
    Description: Specifies the maximum number of iovecs to allocate for RMA
        operations to/from noncontiguous buffers.
    Default: 16384

MPIR_CVAR_CH4_OFI_NUM_PACK_BUFFERS_PER_CHUNK
    Aliases: MPIR_PARAM_CH4_OFI_NUM_PACK_BUFFERS_PER_CHUNK
             MPICH_CH4_OFI_NUM_PACK_BUFFERS_PER_CHUNK
    Description: Specifies the number of buffers for packing/unpacking
        messages in each block of the pool.
    Default: 16

MPIR_CVAR_CH4_OFI_MAX_NUM_PACK_BUFFERS
    Aliases: MPIR_PARAM_CH4_OFI_MAX_NUM_PACK_BUFFERS
             MPICH_CH4_OFI_MAX_NUM_PACK_BUFFERS
    Description: Specifies the max number of buffers for packing/unpacking
        messages in the pool.
    Default: 256

MPIR_CVAR_CH4_OFI_EAGER_MAX_MSG_SIZE
    Aliases: MPIR_PARAM_CH4_OFI_EAGER_MAX_MSG_SIZE
             MPICH_CH4_OFI_EAGER_MAX_MSG_SIZE
    Description: This cvar controls the message size at which OFI native
        path switches from eager to rendezvous mode. It does not affect the
        AM path eager limit. Having this gives a way to reliably test
        native non-path. If the number is positive, OFI will init the
        MPIDI_OFI_global.max_msg_size to the value of cvar. If the number
        is negative, OFI will init the MPIDI_OFI_globa.max_msg_size using
        whatever provider gives (which might be unlimited for socket
        provider).
    Default: -1

MPIR_CVAR_CH4_UCX_MAX_VNIS
    Aliases: MPIR_PARAM_CH4_UCX_MAX_VNIS
             MPICH_CH4_UCX_MAX_VNIS
    Description: If set to positive, this CVAR specifies the maximum number
        of CH4 VNIs that UCX netmod exposes. If set to 0 (the default) or
        bigger than MPIR_CVAR_CH4_NUM_VCIS, the number of exposed VNIs is
        set to MPIR_CVAR_CH4_NUM_VCIS.
    Default: 0

MPIR_CVAR_CH4_IPC_GPU_HANDLE_CACHE
    Aliases: MPIR_PARAM_CH4_IPC_GPU_HANDLE_CACHE
             MPICH_CH4_IPC_GPU_HANDLE_CACHE
    Description: By default, we will cache ipc handle. To manually disable
        ipc handle cache, user can set this variable to 0.
    Default: 1

MPIR_CVAR_CH4_IPC_GPU_P2P_THRESHOLD
    Aliases: MPIR_PARAM_CH4_IPC_GPU_P2P_THRESHOLD
             MPICH_CH4_IPC_GPU_P2P_THRESHOLD
    Description: If a send message size is greater than or equal to
        MPIR_CVAR_CH4_IPC_GPU_P2P_THRESHOLD (in bytes), then enable
        GPU-based single copy protocol for intranode communication. The
        environment variable is valid only when then GPU IPC shmmod is
        enabled.
    Default: 32768

MPIR_CVAR_CH4_XPMEM_ENABLE
    Aliases: MPIR_PARAM_CH4_XPMEM_ENABLE
             MPICH_CH4_XPMEM_ENABLE
    Description: To manually disable XPMEM set to 0. The environment
        variable is valid only when the XPMEM submodule is enabled.
    Default: 1

MPIR_CVAR_CH4_IPC_XPMEM_P2P_THRESHOLD
    Aliases: MPIR_PARAM_CH4_IPC_XPMEM_P2P_THRESHOLD
             MPICH_CH4_IPC_XPMEM_P2P_THRESHOLD
    Description: If a send message size is greater than or equal to
        MPIR_CVAR_CH4_IPC_XPMEM_P2P_THRESHOLD (in bytes), then enable
        XPMEM-based single copy protocol for intranode communication. The
        environment variable is valid only when the XPMEM submodule is
        enabled.
    Default: 4096

MPIR_CVAR_BCAST_POSIX_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_BCAST_POSIX_INTRA_ALGORITHM
             MPICH_BCAST_POSIX_INTRA_ALGORITHM
    Description: Variable to select algorithm for intra-node bcast
        mpir           - Fallback to MPIR collectives
        release_gather - Force shm optimized algo using release, gather
        primitives
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_CH4_POSIX_COLL_SELECTION_TUNING_JSON_FILE)
    Default: MPIR_CVAR_BCAST_POSIX_INTRA_ALGORITHM_auto

MPIR_CVAR_REDUCE_POSIX_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_REDUCE_POSIX_INTRA_ALGORITHM
             MPICH_REDUCE_POSIX_INTRA_ALGORITHM
    Description: Variable to select algorithm for intra-node reduce
        mpir           - Fallback to MPIR collectives
        release_gather - Force shm optimized algo using release, gather
        primitives
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_CH4_POSIX_COLL_SELECTION_TUNING_JSON_FILE)
    Default: MPIR_CVAR_REDUCE_POSIX_INTRA_ALGORITHM_auto

MPIR_CVAR_ALLREDUCE_POSIX_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_ALLREDUCE_POSIX_INTRA_ALGORITHM
             MPICH_ALLREDUCE_POSIX_INTRA_ALGORITHM
    Description: Variable to select algorithm for intra-node allreduce
        mpir           - Fallback to MPIR collectives
        release_gather - Force shm optimized algo using release, gather
        primitives
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_CH4_POSIX_COLL_SELECTION_TUNING_JSON_FILE)
    Default: MPIR_CVAR_ALLREDUCE_POSIX_INTRA_ALGORITHM_auto

MPIR_CVAR_BARRIER_POSIX_INTRA_ALGORITHM
    Aliases: MPIR_PARAM_BARRIER_POSIX_INTRA_ALGORITHM
             MPICH_BARRIER_POSIX_INTRA_ALGORITHM
    Description: Variable to select algorithm for intra-node barrier
        mpir           - Fallback to MPIR collectives
        release_gather - Force shm optimized algo using release, gather
        primitives
        auto - Internal algorithm selection (can be overridden with
        MPIR_CVAR_CH4_POSIX_COLL_SELECTION_TUNING_JSON_FILE)
    Default: MPIR_CVAR_BARRIER_POSIX_INTRA_ALGORITHM_auto

MPIR_CVAR_POSIX_NUM_COLLS_THRESHOLD
    Aliases: MPIR_PARAM_POSIX_NUM_COLLS_THRESHOLD
             MPICH_POSIX_NUM_COLLS_THRESHOLD
    Description: Use posix optimized collectives (release_gather) only when
        the total number of Bcast, Reduce, Barrier, and Allreduce calls on
        the node level communicator is more than this threshold.
    Default: 5

MPIR_CVAR_CH4_SHM_POSIX_EAGER
    Aliases: MPIR_PARAM_CH4_SHM_POSIX_EAGER
             MPICH_CH4_SHM_POSIX_EAGER
    Description: If non-empty, this cvar specifies which shm posix eager
        module to use
    Default: ""

MPIR_CVAR_CH4_POSIX_COLL_SELECTION_TUNING_JSON_FILE
    Aliases: MPIR_PARAM_CH4_POSIX_COLL_SELECTION_TUNING_JSON_FILE
             MPICH_CH4_POSIX_COLL_SELECTION_TUNING_JSON_FILE
    Description: Defines the location of tuning file.
    Default: ""

MPIR_CVAR_CH4_SHM_POSIX_IQUEUE_NUM_CELLS
    Aliases: MPIR_PARAM_CH4_SHM_POSIX_IQUEUE_NUM_CELLS
             MPICH_CH4_SHM_POSIX_IQUEUE_NUM_CELLS
    Description: The number of cells used for the depth of the iqueue.
    Default: 64

MPIR_CVAR_CH4_SHM_POSIX_IQUEUE_CELL_SIZE
    Aliases: MPIR_PARAM_CH4_SHM_POSIX_IQUEUE_CELL_SIZE
             MPICH_CH4_SHM_POSIX_IQUEUE_CELL_SIZE
    Description: Size of each cell. 4KB * 17 is default to avoid a cache
        aliasing issue.
    Default: 69632

MPIR_CVAR_COLL_SHM_LIMIT_PER_NODE
    Aliases: MPIR_PARAM_COLL_SHM_LIMIT_PER_NODE
             MPICH_COLL_SHM_LIMIT_PER_NODE
    Description: Maximum shared memory created per node for optimized
        intra-node collectives (in KB)
    Default: 65536

MPIR_CVAR_BCAST_INTRANODE_BUFFER_TOTAL_SIZE
    Aliases: MPIR_PARAM_BCAST_INTRANODE_BUFFER_TOTAL_SIZE
             MPICH_BCAST_INTRANODE_BUFFER_TOTAL_SIZE
    Description: Total size of the bcast buffer (in bytes)
    Default: 32768

MPIR_CVAR_BCAST_INTRANODE_NUM_CELLS
    Aliases: MPIR_PARAM_BCAST_INTRANODE_NUM_CELLS
             MPICH_BCAST_INTRANODE_NUM_CELLS
    Description: Number of cells the bcast buffer is divided into
    Default: 4

MPIR_CVAR_REDUCE_INTRANODE_BUFFER_TOTAL_SIZE
    Aliases: MPIR_PARAM_REDUCE_INTRANODE_BUFFER_TOTAL_SIZE
             MPICH_REDUCE_INTRANODE_BUFFER_TOTAL_SIZE
    Description: Total size of the reduce buffer per rank (in bytes)
    Default: 32768

MPIR_CVAR_REDUCE_INTRANODE_NUM_CELLS
    Aliases: MPIR_PARAM_REDUCE_INTRANODE_NUM_CELLS
             MPICH_REDUCE_INTRANODE_NUM_CELLS
    Description: Number of cells the reduce buffer is divided into, for
        each rank
    Default: 4

MPIR_CVAR_BCAST_INTRANODE_TREE_KVAL
    Aliases: MPIR_PARAM_BCAST_INTRANODE_TREE_KVAL
             MPICH_BCAST_INTRANODE_TREE_KVAL
    Description: K value for the kary/knomial tree for intra-node bcast
    Default: 64

MPIR_CVAR_BCAST_INTRANODE_TREE_TYPE
    Aliases: MPIR_PARAM_BCAST_INTRANODE_TREE_TYPE
             MPICH_BCAST_INTRANODE_TREE_TYPE
    Description: Tree type for intra-node bcast tree kary      - kary tree
        type knomial_1 - knomial_1 tree type (ranks are added in order from
        the left side) knomial_2 - knomial_2 tree type (ranks are added in
        order from the right side)
    Default: "kary"

MPIR_CVAR_REDUCE_INTRANODE_TREE_KVAL
    Aliases: MPIR_PARAM_REDUCE_INTRANODE_TREE_KVAL
             MPICH_REDUCE_INTRANODE_TREE_KVAL
    Description: K value for the kary/knomial tree for intra-node reduce
    Default: 4

MPIR_CVAR_REDUCE_INTRANODE_TREE_TYPE
    Aliases: MPIR_PARAM_REDUCE_INTRANODE_TREE_TYPE
             MPICH_REDUCE_INTRANODE_TREE_TYPE
    Description: Tree type for intra-node reduce tree kary      - kary tree
        type knomial_1 - knomial_1 tree type (ranks are added in order from
        the left side) knomial_2 - knomial_2 tree type (ranks are added in
        order from the right side)
    Default: "kary"

MPIR_CVAR_ENABLE_INTRANODE_TOPOLOGY_AWARE_TREES
    Aliases: MPIR_PARAM_ENABLE_INTRANODE_TOPOLOGY_AWARE_TREES
             MPICH_ENABLE_INTRANODE_TOPOLOGY_AWARE_TREES
    Description: Enable collective specific intra-node trees which leverage
        the memory hierarchy of a machine. Depends on hwloc to extract the
        binding information of each rank. Pick a leader rank per package
        (socket), then create a per_package tree for ranks on a same
        package, package leaders tree for package leaders. For Bcast -
        Assemble the per_package and package_leaders tree in such a way
        that leaders interact among themselves first before interacting
        with package local ranks. Both the package_leaders and per_package
        trees are left skewed (children are added from left to right, first
        child to be added is the first one to be processed in traversal)
        For Reduce - Assemble the per_package and package_leaders tree in
        such a way that a leader rank interacts with its package local
        ranks first, then with the other package leaders. Both the
        per_package and package_leaders tree is right skewed (children are
        added in reverse order, first child to be added is the last one to
        be processed in traversal) The tree radix and tree type of
        package_leaders and per_package tree is
        MPIR_CVAR_BCAST{REDUCE}_INTRANODE_TREE_KVAL and
        MPIR_CVAR_BCAST{REDUCE}_INTRANODE_TREE_TYPE respectively for bast
        and reduce. But of as now topology aware trees are only kary.
        knomial is to be implemented.
    Default: 1

MPIR_CVAR_CH4_NETMOD
    Aliases: MPIR_PARAM_CH4_NETMOD
             MPICH_CH4_NETMOD
    Description: If non-empty, this cvar specifies which network module to
        use
    Default: ""

MPIR_CVAR_CH4_SHM
    Aliases: MPIR_PARAM_CH4_SHM
             MPICH_CH4_SHM
    Description: If non-empty, this cvar specifies which shm module to use
    Default: ""

MPIR_CVAR_CH4_ROOTS_ONLY_PMI
    Aliases: MPIR_PARAM_CH4_ROOTS_ONLY_PMI
             MPICH_CH4_ROOTS_ONLY_PMI
    Description: Enables an optimized business card exchange over PMI for
        node root processes only.
    Default: 0

MPIR_CVAR_CH4_RUNTIME_CONF_DEBUG
    Aliases: MPIR_PARAM_CH4_RUNTIME_CONF_DEBUG
             MPICH_CH4_RUNTIME_CONF_DEBUG
    Description: If enabled, CH4-level runtime configurations are printed
        out
    Default: 0

MPIR_CVAR_CH4_MT_MODEL
    Aliases: MPIR_PARAM_CH4_MT_MODEL
             MPICH_CH4_MT_MODEL
    Description: Specifies the CH4 multi-threading model. Possible values
        are: direct (default) handoff
    Default: ""

MPIR_CVAR_CH4_NUM_VCIS
    Aliases: MPIR_PARAM_CH4_NUM_VCIS
             MPICH_CH4_NUM_VCIS
    Description: Sets the number of VCIs that user needs (should be a
        subset of MPIDI_CH4_MAX_VCIS).
    Default: 1

MPIR_CVAR_CH4_COLL_SELECTION_TUNING_JSON_FILE
    Aliases: MPIR_PARAM_CH4_COLL_SELECTION_TUNING_JSON_FILE
             MPICH_CH4_COLL_SELECTION_TUNING_JSON_FILE
    Description: Defines the location of tuning file.
    Default: ""

MPIR_CVAR_CH4_IOV_DENSITY_MIN
    Aliases: MPIR_PARAM_CH4_IOV_DENSITY_MIN
             MPICH_CH4_IOV_DENSITY_MIN
    Description: Defines the threshold of high-density datatype. The
        density is calculated by (datatype_size /
        datatype_num_contig_blocks).
    Default: 16384

MPIR_CVAR_CH4_COMM_CONNECT_TIMEOUT
    Aliases: MPIR_PARAM_CH4_COMM_CONNECT_TIMEOUT
             MPICH_CH4_COMM_CONNECT_TIMEOUT
    Description: The default time out period in seconds for a connection
        attempt to the server communicator where the named port exists but
        no pending accept. User can change the value for a specified
        connection through its info argument.
    Default: 180

MPIR_CVAR_CH4_RMA_MEM_EFFICIENT
    Aliases: MPIR_PARAM_CH4_RMA_MEM_EFFICIENT
             MPICH_CH4_RMA_MEM_EFFICIENT
    Description: If true, memory-saving mode is on, per-target object is
        released at the epoch end call. If false, performance-efficient
        mode is on, all allocated target objects are cached and freed at
        win_finalize.
    Default: 0

MPIR_CVAR_CH4_RMA_ENABLE_DYNAMIC_AM_PROGRESS
    Aliases: MPIR_PARAM_CH4_RMA_ENABLE_DYNAMIC_AM_PROGRESS
             MPICH_CH4_RMA_ENABLE_DYNAMIC_AM_PROGRESS
    Description: If true, allows RMA synchronization calls to dynamically
        reduce the frequency of internal progress polling for incoming RMA
        active messages received on the target process. The RMA
        synchronization call initially polls progress with a low frequency
        (defined by MPIR_CVAR_CH4_RMA_AM_PROGRESS_LOW_FREQ_INTERVAL) to
        reduce synchronization overhead. Once any RMA active message has
        been received, it will always poll progress once at every
        synchronization call to ensure prompt target-side progress.
        Effective only for passive target synchronization
        MPI_Win_flush{_all} and MPI_Win_flush_local{_all}.
    Default: 0

MPIR_CVAR_CH4_RMA_AM_PROGRESS_INTERVAL
    Aliases: MPIR_PARAM_CH4_RMA_AM_PROGRESS_INTERVAL
             MPICH_CH4_RMA_AM_PROGRESS_INTERVAL
    Description: Specifies a static interval of progress polling for
        incoming RMA active messages received on the target process.
        Effective only for passive-target synchronization
        MPI_Win_flush{_all} and MPI_Win_flush_local{_all}. Interval
        indicates the number of performed flush calls before polling. It is
        counted globally across all windows. Invalid when
        MPIR_CVAR_CH4_RMA_ENABLE_DYNAMIC_AM_PROGRESS is true.
    Default: 1

MPIR_CVAR_CH4_RMA_AM_PROGRESS_LOW_FREQ_INTERVAL
    Aliases: MPIR_PARAM_CH4_RMA_AM_PROGRESS_LOW_FREQ_INTERVAL
             MPICH_CH4_RMA_AM_PROGRESS_LOW_FREQ_INTERVAL
    Description: Specifies the interval of progress polling with low
        frequency for incoming RMA active message received on the target
        process. Effective only for passive-target synchronization
        MPI_Win_flush{_all} and MPI_Win_flush_local{_all}. Interval
        indicates the number of performed flush calls before polling. It is
        counted globally across all windows. Used when
        MPIR_CVAR_CH4_RMA_ENABLE_DYNAMIC_AM_PROGRESS is true.
    Default: 100

MPIR_CVAR_ENABLE_HCOLL
    Aliases: MPIR_PARAM_ENABLE_HCOLL
             MPICH_ENABLE_HCOLL
    Description: Enable hcoll collective support.
    Default: 0

MPIR_CVAR_COLL_SCHED_DUMP
    Aliases: MPIR_PARAM_COLL_SCHED_DUMP
             MPICH_COLL_SCHED_DUMP
    Description: Print schedule data for nonblocking collective operations.
    Default: 0

MPIR_CVAR_SHM_RANDOM_ADDR_RETRY
    Aliases: MPIR_PARAM_SHM_RANDOM_ADDR_RETRY
             MPICH_SHM_RANDOM_ADDR_RETRY
    Description: The default number of retries for generating a random
        address. A retrying involves only local operations.
    Default: 100

MPIR_CVAR_SHM_SYMHEAP_RETRY
    Aliases: MPIR_PARAM_SHM_SYMHEAP_RETRY
             MPICH_SHM_SYMHEAP_RETRY
    Description: The default number of retries for allocating a symmetric
        heap in shared memory. A retrying involves collective communication
        over the group in the shared memory.
    Default: 100

