PMREORDER(1)

NAME

pmreorder - performs a persistent consistency check using a store reordering mechanism

SYNOPSIS

    $ python pmreorder <options>

DESCRIPTION

The pmreorder tool is a collection of python scripts designed to parse and replay operations logged by pmemcheck - a persistent memory checking tool.

Pmreorder performs the store reordering between persistent memory barriers - a sequence of flush-fence operations. It uses a consistency checking routine provided in the command line options to check whether files are in a consistent state.

Considering that logging, replaying and reordering of operations are very time consuming, it is recommended to use as few stores as possible in test workloads.

OPTIONS

-h, --help

Prints synopsis and list of options.

-l <store_log>, --logfile <store_log>

The pmemcheck log file to process.

-c <prog|lib>, --checker <prog|lib>

Consistency checker type.

-p <path>, --path <path>

Path to the consistency checker. Checker function has to return 0 for consistent cases and 1 otherwise.

-n <name>, --name <name>

The symbol name of the consistency checking function in the library. Valid only if the checker type is lib.

-o <pmreorder_output>, --output <pmreorder_output>

Set the logger output file.

-e <debug|info|warning|error|critical>,

--output-level <debug|info|warning|error|critical>

Set the output log level.

-r <NoReorderNoCheck|

NoReorderDoCheck|

ReorderFull|

ReorderPartial|

ReorderAccumulative|

ReorderReverseAccumulative>,

--default-engine <NoReorderNoCheck|

NoReorderDoCheck|

ReorderFull|

ReorderPartial|

ReorderAccumulative|

ReorderReverseAccumulative>

Set the initial reorder engine. Default value is NoReorderNoCheck.

-x <cli_macros|config_file>, --extended-macros <cli_macros|config_file>

Assign an engine types to the defined marker.

ENGINES

By default, the NoReorderNoCheck engine is used, which means that for each set of stores, the tool will pass-through all sequences of stores not reordered and will not run consistency checker on them.

To enable different types of the reorder engine and begin proper reordering tests, a number of other engines exist:

•   NoReorderDoCheck - pass-through of unchanged operations. Checks correctness of the stores as they were logged. Useful for operations that do not require fail safety.

    Example:
            input: (a, b, c)
            output: (a, b, c)

•   ReorderAccumulative - checks correctness on a growing subset of the original sequence.

    Example:
            input: (a, b, c)
            output:
                   ()
                   (a)
                   (a, b)
                   (a, b, c)

•   ReorderReverseAccumulative - checks correctness on a reverted growing subset of the original sequence.

    Example:
            input: (a, b, c)
            output:
                   ()
                   (c)
                   (c, b)
                   (c, b, a)

•   ReorderPartial - checks consistency on 3 randomly selected sequences from a set of 1000 combinations of the original log, without repetitions.

     Example:
             input: (a, b, c)
             output:
                    (b, c)
                    (b)
                    (a, b, c)

•   ReorderFull - for each set of stores generates and checks consistency of all possible store permutations. This might prove to be very computationally expensive for most workloads. It can be useful for critical sections of code with limited number of stores.

     Example:
            input: (a, b, c)
            output:
                   ()
                   (a)
                   (b)
                   (c)
                   (a, b)
                   (a, c)
                   (b, a)
                   (b, c)
                   (c, a)
                   (c, b)
                   (a, b, c)
                   (a, c, b)
                   (b, a, c)
                   (b, c, a)
                   (c, a, b)
                   (c, b, a)

When the engine is passed with an -r option, it will be used for each logged set of stores. Additionally, the -x parameter can be used to switch engines separately for any marked code sections. For more details about -x extended macros functionality see section INSTRUMENTATION below.

INSTRUMENTATION

The core of pmreorder is based on user-provided named markers. Sections of code can be `marked' depending on their importance, and the degree of reordering can be customized by the use of various provided engines.

For this purpose, Valgrind's pmemcheck tool exposes a generic marker macro:

•   VALGRIND_PMC_EMIT_LOG(value)

It emits log to store_log during pmemcheck processing. value is a user-defined marker name. For more details about pmemcheck execution see PMEMCHECK STORE LOG section below.

Example:

    main.c
    .
    .
    .
    VALGRIND_PMC_EMIT_LOG("PMREORDER_MEMSET_PERSIST.BEGIN");
    pmem_memset_persist(...);
    VALGRIND_PMC_EMIT_LOG("PMREORDER_MEMSET_PERSIST.END");
    .
    .
    .

There are a few rules for macros creation:

•   Valid macro can have any name, but begin and end section have to match - they are case sensitive.

•   Macro must have .BEGIN or .END suffix.

•   Macros can't be crossed.

Defined markers can be assigned engines types and configured through the pmreorder tool using the -x parameter.

There are two ways to set macro options:

•   Using command line interface in format:

    + Using configuration file in .json format:

{ “PMREORDER_MARKER_NAME1”:“ReorderName1”, “PMREORDER_MARKER_NAME2”:“ReorderName2” }

    For more details about available
    engines types, see ENGINES section above.
    **libpmemobj**(7) also provides set of macros that allows change
    reordering engine on library or function level:
    `<library_name|api_function_name>`
    Example of configuration on function level:

{ “pmemobj_open”:“NoReorderNoCheck”, “pmemobj_memcpy_persist”:“ReorderPartial” }

    Example of configuration on library level
    (affecting all library functions):

{ “libpmemobj”:“NoReorderNoCheck” }

    List of marked **libpmemobj**(7) API functions:

pmemobj_alloc pmemobj_cancel pmemobj_check pmemobj_close pmemobj_create pmemobj_ctl_exec pmemobj_ctl_set pmemobj_free pmemobj_list_insert pmemobj_list_insert_new pmemobj_list_move pmemobj_list_remove pmemobj_memcpy pmemobj_memmove pmemobj_memset pmemobj_memcpy_persist pmemobj_memset_persist pmemobj_open pmemobj_publish pmemobj_realloc pmemobj_reserve pmemobj_root pmemobj_root_construct pmemobj_strdup pmemobj_tx_abort pmemobj_tx_add_range pmemobj_tx_add_range_direct pmemobj_tx_alloc pmemobj_tx_commit pmemobj_tx_free pmemobj_tx_publish pmemobj_tx_realloc pmemobj_tx_strdup pmemobj_tx_wcsdup pmemobj_tx_xadd_range pmemobj_tx_xadd_range_direct pmemobj_tx_xalloc pmemobj_tx_zalloc pmemobj_tx_zrealloc pmemobj_wcsdup pmemobj_xalloc pmemobj_xreserve pmemobj_zalloc pmemobj_zrealloc

    # PMEMCHECK STORE LOG #
    To generate *store_log* for **pmreorder** run pmemcheck
    with additional parameters:

valgrind
–tool=pmemcheck
-q
–log-stores=yes
–print-summary=no
–log-file=store_log.log
–log-stores-stacktraces=yes
–log-stores-stacktraces-depth=2
–expect-fence-after-clflush=yes
test_binary writer_parameter

    For further details of pmemcheck parameters see [pmemcheck documentation](https://github.com/pmem/valgrind/blob/pmem-3.13/pmemcheck/docs/pmc-manual.xml)
    # ENVIRONMENT #
    By default all logging from PMDK libraries is disabled.
    To enable API macros logging set environment variable:
    + **PMREORDER_EMIT_LOG**=1
    # EXAMPLE #

python pmreorder.py
-l store_log.log
-r NoReorderDoCheck
-o pmreorder_out.log
-c prog
-x PMREORDER_MARKER_NAME=ReorderPartial
-p checker_binary checker_parameter ```

Checker binary will be used to run consistency checks on “store_log.log”, output of pmemcheck tool. Any inconsistent stores found during pmreorder analysis will be logged to pmreorder_out.log.

SEE ALSO

<http://pmem.io>