Intel® MPI Library

Developer Reference for Linux* OS

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ID 768732
Date 10/31/2024
Public
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 I_MPI_OFFLOAD I_MPI_OFFLOAD_MODE I_MPI_OFFLOAD_SYMMETRIC I_MPI_OFFLOAD_LEVEL_ZERO_LIBRARY I_MPI_OFFLOAD_CUDA_LIBRARY NIC Pinning 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 I_MPI_OFFLOAD_MODE I_MPI_OFFLOAD_SYMMETRIC I_MPI_OFFLOAD_LEVEL_ZERO_LIBRARY I_MPI_OFFLOAD_CUDA_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
Developer Reference for Linux* OS

GPU Support

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

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

Current support is limited to Intel GPUs and Nvidia* GPUs only.

I_MPI_OFFLOAD

Set this environment variable to enable all GPU features.

Syntax

I_MPI_OFFLOAD=<value>

Arguments

Value Description
0 Disabled. This is the default value.
1 Enabled.

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.

I_MPI_OFFLOAD_MODE

Select the API for GPU/accelerator offloading.

Syntax

I_MPI_OFFLOAD_MODE=<value>

Arguments

Value Description
auto Automatically identify GPU backend. This is the default value.
level_zero Use Level-Zero API and library for GPU operations.
cuda Use CUDA Driver API and library for GPU operations.

Description

Set this environment variable to select the API for GPU/accelerator offloading.

I_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. This is the 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

Argument Description
<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.

I_MPI_OFFLOAD_CUDA_LIBRARY

Specify the name and full path to the CUDA Driver library.

Arguments

Value Description
<path> Full path to the CUDA Driver library.
<name> Name of the CUDA Driver library.

Description

Set this environment variable to specify the name and full path to CUDA Driver library. Set this variable if CUDA is not located in the default path. The default value is ibcuda.so.

See Also

Parent topic: Environment Variable Reference
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