topic Re:About MKL_CBWR code path dispatch in Intel® oneAPI Math Kernel Library

About MKL_CBWR code path dispatch

Bob2023 — Fri, 07 Apr 2023 08:27:21 GMT

My program runs on Intel Xeon Gold 6348, the Linux is RHEL7.8.

Intel Xeon Gold 6348's launch date is Q2'21.

The MKL version is "MKL 2020.0 Product build 20191122 for Intel(R) 64 architecture".

When I set MKL_CBWR to AVX2 and AVX, then run the program, the libmkl_avx512.so and libmkl_vml_avx512.so are loaded. This is not as my expected. When MKL_CBWR=AVX2, I think the libmkl_avx2.so and libmkl_vml_avx2.so will be loaded.

When I set MKL_CBWR=AVX2 and MKL_ENABLE_INSTRUCTIONS=AVX2, the libmkl_avx2.so and libmkl_vml_avx2.so are loaded.

Since 6348 support AVX2, when I just set MKL_CBWR=AVX2, why MKL not load the right library(libmkl_avx2.so and libmkl_vml_avx2.so) ?

Is it because the 6348's launch date(Q2'21) is behind the MKL launch date(20191122) , so the MKL not dispatch the code path to AVX2 even I set MKL_CBWR=AVX2 ?

And why the AVX512 is dispatched ?

Re:About MKL_CBWR code path dispatch

PraneethA_Intel — Mon, 10 Apr 2023 11:11:20 GMT

Hi Bob,

Thanks for posting in Intel communities.

In some cases, Intel oneAPI Math Kernel Library also provides support for upcoming architectures ahead of hardware availability and Intel MKL does not automatically dispatch code path as desired. Hence, you will need to use the MKL_ENABLE_INSTRUCTIONS environment variable or mkl_enable_instructions support function to enable an ISA.

Please refer to the below link for more information.

https://www.intel.com/content/www/us/en/docs/onemkl/developer-guide-windows/2023-0/instruction-set-specific-dispatch-on-intel-archs.html

Thanks and Regards,

Praneeth Achanta

Re:About MKL_CBWR code path dispatch

PraneethA_Intel — Mon, 17 Apr 2023 04:23:06 GMT

Hi Bob,

We have not heard back from you. Could you please provide an update on your issue?

Thanks & Regards,

Praneeth Achanta

Re:About MKL_CBWR code path dispatch

PraneethA_Intel — Thu, 20 Apr 2023 09:24:05 GMT

Hi Bob,

Glad to know your issue was resolved. As per your comments in this thread, we are closing this case. The current thread will no longer be monitored by Intel. If you need any further assistance, please post a new question.

Thanks and Regards,

Praneeth Achanta