Environment Variables

I_MPI_MIC

Syntax

I_MPI_MIC=<value>

Arguments

`<value>`	Intel® Xeon Phi™ recognition
`enable \| yes \| on \| 1`	Enable the Intel Xeon Phi coprocessor recognition
`disable \| no \| off \| 0`	Disables the Intel Xeon Phi coprocessor recognition. This is the default value

Description

Set this environment variable to control whether the Intel Xeon processor of the Intel® MPI Library will try to detect and work with the Intel® MIC Architecture components.

If the value of environment variable I_MPI_MIC is enable, the default value of environment variable I_MPI_SSHM is enable.

If the value of environment variable I_MPI_MIC is enable, the default value of environment variable I_MPI_DAPL_DIRECT_COPY_THRESHOLD is 4906 and 4096,262144 in case of multiple providers availability.

If the value of environment variable I_MPI_MIC is enable, the default value of environment variable I_MPI_DAPL_BUFFER_SIZE is 4352.

Note:

This is a provisional variable and is only temporarily introduced, until the architecture detection and other related matters are clarified.

I_MPI_MIC_PREFIX

Syntax

I_MPI_MIC_PREFIX=<value>

Arguments

<value>

Specify a string as the prefix of an Intel Xeon Phi coprocessor file name. The default value is an empty string

Description

Set this environment variable to add a prefix to a host executable name to get a corresponding Intel Xeon Phi coprocessor executable file name.

For example, set different locations as the value for the I_MPI_MIC_PREFIX environment variable to distinguish Intel MIC Architecture and Intel® 64 Architecture executable files:

(host)$ mpiicc test.c -o test_hello

(host)$ mpiicc -mmic test.c -o ./MIC/test_hello

(host)$ export I_MPI_MIC=1

(host)$ export I_MPI_MIC_PREFIX=./MIC/

(host)$ mpiexec.hydra -n 4 -hostfile <hostfile> test_hello

In the example, ./test_hello binary is launched on Intel® 64 Architecture nodes and ./MIC/test_hello binary is launched on Intel Xeon Phi coprocessor nodes.

I_MPI_MIC_POSTFIX

Syntax

I_MPI_MIC_POSTFIX=<value>

Arguments

<value>

Specify a string as the postfix of an Intel Xeon Phi coprocessor file name. The default value is an empty string

Description

Set this environment variable to add a postfix to a host executable name to get a corresponding Intel Xeon Phi coprocessor executable name.

For example, set different names as the value for the I_MPI_MIC_POSTFIX environment variable to distinguish Intel Xeon Phi coprocessor and Intel 64 Architecture executable files:

(host)$ mpiicc test.c -o test_hello

(host)$ mpiicc -mmic test.c -o test_hello.mic

(host)$ export I_MPI_MIC=1

(host)$ export I_MPI_MIC_POSTFIX=.mic

(host)$ mpiexec.hydra -n 4 -hostfile <hostfile> test_hello

In the example, test_hello binary is launched on Intel 64 Architecture nodes and test_hello.mic binary on Intel Xeon Phi coprocessor nodes.

I_MPI_DAPL_PROVIDER_LIST

Syntax

I_MPI_DAPL_PROVIDER_LIST=<primary provider>[,<local secondary provider> [,<remote secondary provider>]]

Arguments

`<primary provider>`	Provides the best latency and available on all network segments (cross box and within box)
`<local secondary provider>`	Provides the best bandwidth for local configurations (within box)
`<remote secondary provider>`	Provides best bandwidth for remote configurations (cross box)

Description

Use this variable to define the DAPL providers to load.

With Intel® Manycore Platform Software Stack (Intel® MPSS), the arguments of I_MPI_DAPL_PROVIDER_LIST are set as the following values:

<primary provider>- CCL-direct
<local secondary provider>- IBSCIF
<remote secondary provider>- CCL-proxy

Thus, the setting is I_MPI_DAPL_PROVIDER_LIST=<CCL-direct>[,<IBSCIF>[,<CCL-proxy>]]

The following configuration is an example with the default dat.conf provided with Intel MPSS:

I_MPI_DAPL_PROVIDER_LIST=ofa-v2-mlx4_0-1u,ofa-v2-scif0,ofa-v2-mcm-1

You can adjust the threshold for secondary provider through the I_MPI_DAPL_DIRECT_COPY_THRESHOLD environment variable (<secondary provider threshold>):

I_MPI_DAPL_DIRECT_COPY_THRESHOLD=<primary provider direct copy threshold>[,<secondary provider threshold>]

<primary provider direct copy threshold> has to be lower than <secondary provider threshold>.

If the environment variable I_MPI_DAPL_PROVIDER_LIST contains a list of values, then the syntax of the following environment variables may be extended by the values related to all corresponding providers.

I_MPI_DAPL_DIRECT_COPY_THRESHOLD
I_MPI_DAPL_TRANSLATION_CACHE
I_MPI_DAPL_TRANSLATION_CACHE_AVL_TREE
I_MPI_DAPL_CONN_EVD_SIZE
I_MPI_DAPL_RDMA_RNDV_WRITE

If only single value is set, this value applies to all providers. In case of mismatch or incorrect values, the default value is used for all providers.

For example:

export I_MPI_DAPL_PROVIDER_LIST=ofa-v2-mlx4_0-1,ofa-v2-scif0

export I_MPI_DAPL_TRANSLATION_CACHE=enable,disable

This I_MPI_DAPL_TRANSLATION_CACHE setting turns on the memory registration cache for the first provider; but turns it off for the second one.

I_MPI_ENV_PREFIX_LIST

Define the prefixes of environment variables for the intended platforms.

Syntax

I_MPI_ENV_PREFIX_LIST=[platform:prefix][,...]

Argument

platform

The intended platform (string).

Options: htn,nhm,wsm,snb,ivb

See I_MPI_PLATFORM for the detail options descriptions

prefix

A prefix (string) for a name of an environment variable to be used for the intended platform

Description

Set this environment variable to define the prefix of environment variables to be used for the intended platform.

If you specify a prefix in I_MPI_ENV_PREFIX_LISTfor an environment variable, the prefixed environment variable overrides the respective non-prefixed environment variable on the intended platform.

If you do not specify I_MPI_ENV_PREFIX_LIST, environment variables are applied to all platforms.

Note:

Use the lower case when you specify the platform names.

Examples

I_MPI_ENV_PREFIX_LIST=platform:prefix

<NAME>=valueis applied to all systems.

<prefix>_<NAME>=value defines <NAME>=value for all <platform> systems.
Assume that some machines are on the Intel® microarchitecture code name Sandy Bridge based platform, and the rest machines are on other architectures based platforms. The environment variable OMP_NUM_THREADS value is 3 on all platforms.

To set OMP_NUM_THREADS=5 for the ranks on the Intel® microarchitecture code name Sandy Bridge based platform, specify the prefix in I_MPI_ENV_PREFIX_LISTfor OMP_NUM_THREADS with the following configurations:

I_MPI_ENV_PREFIX_LIST=snb:<prefix> OMP_NUM_THREADS=3 <prefix>_OMP_NUM_THREADS=5