topic How can I get the default value of mpi environment variables? in Intel® MPI Library

How can I get the default value of mpi environment variables?

oleotiger — Mon, 24 May 2021 01:48:43 GMT

I wanna get the default value of some mpi environment variables.

For example:

I_MPI_SHM_CELL_FWD_SIZE

I_MPI_SPIN_COUNT

I tried Debug lv =5 but there is still no default value of these variables in output.

How could I get those default values?

BTW: can someone explain the details about I_MPI_SHM_CELL_FWD_SIZE? Any documentations that can help me?

Re:How can I get the default value of mpi environment variables?

ShivaniK_Intel — Mon, 24 May 2021 12:36:32 GMT

Hi,

Thanks for reaching out to us.

The default value of the environment variable for I_MPI_SHM_CELL_FWD_SIZE.

The default value depends on the transport used and should normally range from 64K to 1024K.

For detailed information please refer to the below link.

https://software.intel.com/content/www/us/en/develop/documentation/mpi-developer-reference-linux/top/environment-variable-reference/environment-variables-for-fabrics-control/shared-memory-control.html

To get the default value of the environment variable for I_MPI_SPIN_COUNT.

The default setting is 250 unless more than one process runs per processor, in which case it is set to 1.

For more information please refer to the below link

https://software.intel.com/content/www/us/en/develop/articles/tuning-the-intel-mpi-library-advanced-techniques.html

Thanks & Regards

Shivani

Re: Re:How can I get the default value of mpi environment variables?

oleotiger — Mon, 24 May 2021 14:33:35 GMT

I have read the documentation. But they didn't solve my question.

The value of I_MPI_SHM_CELL_FWD_SIZE depends on the transport used and range from64K to 1024K. But I wanna know the exact value of I_MPI_SHM_CELL_FWD_SIZE on my server.

The server is equipped with Mellonax CX-5 IB network card and the protocol I used is IB.

OFI provider is mlx and ofi is set by default.

What is the exact value of I_MPI_SHM_CELL_FWD_SIZE under this environment?

What if I change to Huawei 1822 network card and use RoCE protocol?

Is there any way that I could get the exact value of I_MPI_SHM_CELL_FWD_SIZE? (e.g. through log or documentation which lists all the default values for all transports?)

Re:How can I get the default value of mpi environment variables?

ShivaniK_Intel — Mon, 31 May 2021 07:32:58 GMT

Hi,

We are working on it and will get back to you soon.

Thanks & Regards

Shivani

Re:How can I get the default value of mpi environment variables?

DrAmarpal_K_Intel — Mon, 07 Jun 2021 09:48:49 GMT

Hi Oleotiger,

[1] Please disregard the earlier comment in this thread on the default value of I_MPI_SPIN_COUNT. In the current versions of Intel MPI Library, the default value value is equal to 1 when more than one process runs per processor/core. Otherwise the value equals 2000.

[2] In regard to I_MPI_SHM_CELL_FWD_SIZE, I shall write another message.

Best regards,

Amar

Re:How can I get the default value of mpi environment variables?

DrAmarpal_K_Intel — Fri, 18 Jun 2021 10:53:02 GMT

Hi Oleotiger,

Is there anything else I can help you with?

Best regards,

Amar

Re:How can I get the default value of mpi environment variables?

DrAmarpal_K_Intel — Fri, 25 Jun 2021 07:31:38 GMT

Hi Oleotiger,

Having not received your response I am going ahead and closing this thread.

We will no longer respond to this thread. If you require additional assistance from Intel, please start a new thread. Any further interaction in this thread will be considered community only.