topic Hi vasci_ in Intel® oneAPI Math Kernel Library

Any known issues with dcopy ( MKL 11.2.4) in multithread environment?

AndrewC — Thu, 26 May 2016 21:45:49 GMT

My software seems to be 'randomly' deadlocking inside dcopy. I have lots of threads running. Is this a known issue? Running Intel Inspector XE always shows a litany of data race issues inside MKL but I have always been told 'don't worry, they are ok'.

     ntdll.dll!000000007750d3fa()
    [Frames below may be incorrect and/or missing, no symbols loaded for ntdll.dll]
    KernelBase.dll!000007fefd4110ac()
    libiomp5md.dll!000007fed0c747a0()
    libiomp5md.dll!000007fed0c08977()
    libiomp5md.dll!000007fed0c0ce40()
    libiomp5md.dll!000007fed0c3d7d1()
    libiomp5md.dll!000007fed0c0e736()
    mkl_intel_thread.dll!000007fea7a9baa5()
    mkl_intel_thread.dll!000007fea7a0b611()
     xxxxx.dll!dcopy() + 0x7a bytes

Hi vasci_i,

Ying_H_Intel — Mon, 30 May 2016 02:55:53 GMT

Hi vasci_i,

Could you build a small test case to reproduce the problem?

I tried one small case, (with MKL dcopy call in MKL example folder). the inspector reports "No problem detected".

Best Regards,
Ying

Intel inspector does not give

AndrewC — Mon, 30 May 2016 06:17:39 GMT

Intel inspector does not give specific warnings on DCOPY. I do find a number of warnings about data races on various LAPACK functions.

Anyway,this error occurred under very heavy threading conditions. Nested OMP threading , when called from separate threads. By reducing the # of threads the problem resolved itself. Upgrading to MKL 11.3.4 also corrected the issue.

Hi vasci_

Ying_H_Intel — Wed, 01 Jun 2016 05:55:18 GMT

Hi vasci_

Thanks for sharing the result.

There are some work between intel inspector and us to remove the MKL's warning in their report. So it was improved along later version.

Thanks

Ying

Here is MKL bug fix.

https://software.intel.com/en-us/articles/intel-mkl-113-bug-fixes-list