Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 7/13/2023
Public

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mkl_free_buffers

Frees unused memory allocated by the Intel® oneAPI Math Kernel Library (oneMKL) on the Host.

Syntax

call mkl_free_buffers

Fortran Include Files/Modules

  • Include file: mkl.fi
  • Module (compiled): mkl_service.mod
  • Module (source): mkl_service.f90

Description

To improve performance of Intel® oneAPI Math Kernel Library (oneMKL) on CPU, the Memory Allocator uses per-thread memory pools where buffers may be collected for fast reuse. Intel® oneAPI Math Kernel Library (oneMKL) also allocates temporary buffers on the host memory to improve performance of GPU kernels. The mkl_free_buffers function frees both types of memory.

See theIntel® oneAPI Math Kernel Library (oneMKL) Developer Guide for details.

You should call mkl_free_buffers after the last call to Intel® oneAPI Math Kernel Library (oneMKL) functions. In large applications, if you suspect that the memory may get insufficient, you may call this function earlier, but anticipate a drop in performance that may occur due to reallocation of buffers for subsequent calls to Intel® oneAPI Math Kernel Library (oneMKL) functions.

Product and Performance Information

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.

Notice revision #20201201

Usage of mkl_free_buffers with FFT Functions (C Example)

DFTI_DESCRIPTOR_HANDLE hand1; 
DFTI_DESCRIPTOR_HANDLE hand2; 
void mkl_free_buffers(void);
. . . . . .
/* Using Intel MKL FFT */
Status = DftiCreateDescriptor(&hand1, DFTI_SINGLE, DFTI_COMPLEX, dim, m1); 
Status = DftiCommitDescriptor(hand1);
Status = DftiComputeForward(hand1, s_array1);
. . . . . .
Status = DftiCreateDescriptor(&hand2, DFTI_SINGLE, DFTI_COMPLEX, dim, m2); 
Status = DftiCommitDescriptor(hand2);
. . . . . .
Status = DftiFreeDescriptor(&hand1);
. . . . . .
Status = DftiComputeBackward(hand2, s_array2)); 
Status = DftiFreeDescriptor(&hand2);
/* Here you finish using Intel MKL FFT */
/* Memory leak will be triggered by any memory control tool */
/* Use mkl_free_buffers() to avoid memory leaking */
mkl_free_buffers();