Intel® MPI Library

Developer Reference for Linux* OS

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ID 768732
Date 10/31/2024
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Document Table of Contents
Document Table of Contents x
Developer Reference for Linux* OS
Developer Reference for Linux* OS x
Introduction Command Reference Environment Variable Reference Miscellaneous Notices and Disclaimers
Introduction x
Introducing Intel® MPI Library Notational Conventions Related Information
Command Reference x
Compiler Commands mpirun mpiexec.hydra cpuinfo impi_info mpitune_fast
Compiler Commands x
Compilation Command Options
mpiexec.hydra x
Global Hydra Options Local Hydra Options gtool Options
Environment Variable Reference x
Compilation Environment Variables Hydra Environment Variables I_MPI_ADJUST Family Environment Variables Tuning Environment Variables Process Pinning GPU Support NIC Pinning Environment Variables for Fabrics Control Environment Variables for Memory Policy Control Environment Variables for Asynchronous Progress Control I_MPI_ASYNC_PROGRESS I_MPI_ASYNC_PROGRESS_THREADS I_MPI_ASYNC_PROGRESS_PIN I_MPI_ASYNC_PROGRESS_ID_KEY Environment Variables for Multi-EP Other Environment Variables
Tuning Environment Variables x
Autotuning
Autotuning x
I_MPI_TUNING_AUTO Family Environment Variables
Process Pinning x
Environment Variables for Process Pinning Interoperability with OpenMP* API
GPU Support x
GPU Pinning GPU Buffers Support
Environment Variables for Fabrics Control x
Communication Fabrics Control Shared Memory Control OFI*-capable Network Fabrics Control
Miscellaneous x
Java* Bindings for MPI-2 Routines
Developer Reference for Linux* OS

Environment Variables for Asynchronous Progress Control

I_MPI_ASYNC_PROGRESS

Control the usage of progress threads.

Syntax

I_MPI_ASYNC_PROGRESS=<arg>

Arguments

<arg> Binary indicator
disable | no | off | 0 Disable asynchronous progress threads for each rank. This is the default value.
enable | yes | on | 1 Enable asynchronous progress threads.

Description

Set this environment variable to enable asynchronous progress. If disabled, the I_MPI_ASYNC_PROGRESS_* knobs are ignored.

I_MPI_ASYNC_PROGRESS_THREADS

Control the number of asynchronous progress threads.

Syntax

I_MPI_ASYNC_PROGRESS_THREADS=<arg>

Arguments

<nthreads> Define the number of progress threads. The default value is 1.

Description

Set this environment variable to control the number of asynchronous progress threads for each rank.

I_MPI_ASYNC_PROGRESS_PIN

Control the asynchronous progress threads pinning.

Syntax

I_MPI_ASYNC_PROGRESS_PIN=<arg>

Arguments

<arg> Comma-separated list of logical processors
<CPU list> Pin all progress threads of local processes to the listed CPUs. By default, N progress threads are pinned to the last N logical processors.

Description

Set this environment variable to control pinning for all progress threads of local processes.

Example 

I_MPI_ASYNC_PROGRESS_THREADS=3
I_MPI_ASYNC_PROGRESS_PIN="0,1,2,3,4,5"

In case of three MPI processes per node, progress threads of the first process are pinned to 0, 1, second are pinned to 2, 3, and third are pinned to 4, 5.

I_MPI_ASYNC_PROGRESS_ID_KEY

Set the MPI info object key that is used to explicitly define the progress thread id for a communicator.

Syntax

I_MPI_ASYNC_PROGRESS_ID_KEY=<arg>

Arguments

<key> MPI info object key. The default value is thread_id.

Description

Set this environment variable to control the MPI info object key that is used to define the progress thread id for a communicator. The progress thread id is used for work distribution between progress threads. By default, communication goes over the first progress thread.

NOTE:

Exclude selected processors for progress threads from pinning of computational threads to avoid oversubscription of cores.

For more information and examples, refer to the Intel® MPI Library Developer Guide, section Asynchronous Progress Control.

Parent topic: Environment Variable Reference
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