Intel® MPI Library Developer Reference for Linux* OS

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ID 768732
Date 3/31/2023
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Document Table of Contents
Document Table of Contents x
Intel® MPI Library Developer Reference for Linux* OS
Intel® MPI Library Developer Reference for Linux* OS x
Introduction Command Reference Environment Variable Reference Miscellaneous Notices and Disclaimers
Introduction x
Introducing Intel® MPI Library What's New Notational Conventions Related Information
Command Reference x
Compiler Commands mpirun mpiexec.hydra cpuinfo impi_info mpitune mpitune_fast
Compiler Commands x
Compilation Command Options
mpiexec.hydra x
Global Hydra Options Local Hydra Options gtool Options
mpitune x
mpitune Configuration Options
Environment Variable Reference x
Compilation Environment Variables Hydra Environment Variables I_MPI_ADJUST Family Environment Variables Tuning Environment Variables Process Pinning GPU Support I_MPI_OFFLOAD _MPI_OFFLOAD_SYMMETRIC I_MPI_OFFLOAD_LEVEL_ZERO_LIBRARY Environment Variables for Fabrics Control Environment Variables for Memory Policy Control Environment Variables for Asynchronous Progress Control 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
I_MPI_OFFLOAD _MPI_OFFLOAD_SYMMETRIC I_MPI_OFFLOAD_LEVEL_ZERO_LIBRARY 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
Intel® MPI Library Developer Reference for Linux* OS

GPU Support

This section provides information about the following GPU devices support in Intel® MPI Library:

  1. GPU pinning
  2. GPU buffers support

These features require the Level-Zero* library to be installed on the nodes. All environment variables have I_MPI_OFFLOAD_* prefix.

Current support is limited to Intel® GPUs only.

I_MPI_OFFLOAD

Set this environment variable to enable all GPU features.

Syntax

I_MPI_OFFLOAD=<value>

Arguments

Value Description
0 Disabled (default value)
1 Auto. Intel MPI expects that libze_loader.so is already loaded and does not load it twice
2 Enabled. Intel MPI loads libze_loader.so

Description

Set this environment variable to enable all GPU features such as GPU pinning and GPU buffers support, which give you ability to distribute devices between MPI ranks and provide a pointer of an offloaded memory to MPI functions.

_MPI_OFFLOAD_SYMMETRIC

Enable/disable an assumption that all buffers in an operation have the same type.

Syntax

I_MPI_OFFLOAD_SYMMETRIC=<value>

Arguments

Value Description
0 Disabled (default value)
1 Enabled

Description

Set this environment variable to enable/disable an assumption that all buffers in an operation have the same type. That is, buffers are allocated on GPU or HOST only.

Setting this variable optimizes device->device communications but disables handling of host->device and device->host cases.

I_MPI_OFFLOAD_LEVEL_ZERO_LIBRARY

Specify the name and full path to the Level-Zero library.

Syntax

I_MPI_OFFLOAD_LEVEL_ZERO_LIBRARY="<path>/<name>"

Arguments

<path>   Full path to the Level-Zero library.

<name> Name of the Level-Zero library.

Description

Set this environment variable to specify the name and full path to Level-Zero library. Set this variable if Level-Zero is not located in the default path. Default value: libze_loader.so.

Parent topic: Environment Variable Reference
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