Call Description Line

In Intel MKL Verbose mode, each verbose-enabled function called from your application prints a call description line. The line begins with the MKL_VERBOSE character string and uses spaces as delimiters. The format of the rest of the line may change in a future release.

The following table lists information contained in a call description line and provides available links for more information:



Related Links

The name of the function.

Although the name printed may differ from the name used in the source code of the application (for example, the cblas_ prefix of CBLAS functions is not printed), you can easily recognize the function by the printed name.


Values of the arguments.

  • The values are listed in the order of the formal argument list. The list directly follows the function name, it is parenthesized and comma-separated.
  • Arrays are printed as addresses (to see the alignment of the data).
  • Integer scalar parameters passed by reference are printed by value. Zero values are printed for NULL references.
  • Character values are printed without quotes.
  • For all parameters passed by reference, the values printed are the values returned by the function. For example, the printed value of the info parameter of a LAPACK function is its value after the function execution.

Time taken by the function.

  • The time is printed in convenient units (seconds, milliseconds, and so on), which are explicitly indicated.

  • The time may fluctuate from run to run.

  • The time printed may occasionally be larger than the time actually taken by the function call, especially for small problem sizes and multi-socket machines. To reduce this effect, bind threads that call Intel MKL to CPU cores by setting an affinity mask.

Managing Multi-core Performance for options to set an affinity mask.

Value of the MKL_CBWR environment variable.

The value printed is prefixed with CNR:

Getting Started with Conditional Numerical Reproducibility

Value of the MKL_DYNAMIC environment variable.

The value printed is prefixed with Dyn:


Status of the Intel MKL memory manager.

The value printed is prefixed with FastMM:

Avoiding Memory Leaks in Intel MKL for a description of the Intel MKL memory manager

OpenMP* thread number of the calling thread.

The value printed is prefixed with TID:


Values of Intel MKL environment variables defining the general and domain-specific numbers of threads, separated by a comma.

The first value printed is prefixed with NThr:

Intel MKL-specific Environment Variables for Threading Control

The following is an example of a call description line:

MKL_VERBOSE DGEMM(n,n,1000,1000,240,0x7ffff708bb30,0x7ff2aea4c000,1000,0x7ff28e92b000,240,0x7ffff708bb38,0x7ff28e08d000,1000) 1.66ms CNR:OFF Dyn:1 FastMM:1 TID:0 NThr:16,FFT:2 WDiv:HOST:-1.000 WDiv:0:-1.000 WDiv:1:-1.000

The following information is not printed because of limitations of Intel MKL Verbose mode:

  • Input values of parameters passed by reference if the values were changed by the function.

    For example, if a LAPACK function is called with a workspace query, that is, the value of the lwork parameter equals -1 on input, the call description line prints the result of the query and not -1.

  • Return values of functions.

    For example, the value returned by the function ilaenv is not printed.

  • Floating-point scalars passed by reference.

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