Intel® MPI Benchmarks User Guide and Methodology Description

# Exchange

Exchange is a communication pattern that often occurs in grid splitting algorithms (boundary exchanges). The group of processes is similar to a periodic chain, and each process exchanges data with both left and right neighbor in the chain.

The turnover count is four messages per sample (two in, two out) for each process.

For two `Isend` messages, separate buffers are used.

## Exchange Definition

Property | Description
--- | ---
Measured pattern | As symbolized between in the figure below.
MPI routines | `MPI_Isend/MPI_Waitall, MPI_Recv`
MPI data type | `MPI_BYTE`
Reported timings | `time=Δt` (in `μsec`)
Reported throughput | `4X/time`

## Exchange Pattern