Intel® MPI Benchmarks User Guide and Methodology Description

# Ireduce_scatter_pure

The benchmark for the `MPI_Ireduce_scatter` function that measures pure communication time. It reduces a vector of length `L = X/sizeof(float)` float items. The MPI data type is `MPI_FLOAT`. The MPI operation is `MPI_SUM`. In the scatter phase, the `L` items are split as evenly as possible. To be exact, for `np` number of processes:

`L = r*np+s`

where

- `r = ⌊L/np⌋`

- `s = L mod np`

In this case, the process with rank `i` gets:

- `r+1` items when `i<s`

- `r` items when `is`

Property | Description
--- | ---
Measured pattern | `MPI_Ireduce_scatter/MPI_Wait`
MPI data type | `MPI_FLOAT`
MPI operation | `MPI_SUM`
Reported timings | Bare time
Reported throughput | None