Intel® oneAPI Math Kernel Library Developer Reference - C
Use the conditional numerical reproducibility (CNR) functionality in Intel® oneAPI Math Kernel Library to obtain reproducible results from MKL routines. When enabling CNR, you choose a specific code branch of Intel® oneAPI Math Kernel Library that corresponds to the instruction set architecture (ISA) that you target. Use these named constants to specify the code branch and other CNR options.
Named Constant |
Value |
Description |
|---|---|---|
| CNR Branches | ||
MKL_CBWR_OFF |
0 |
Disable CNR mode |
MKL_CBWR_BRANCH_OFF |
1 |
CNR mode is disabled |
MKL_CBWR_AUTO |
2 |
Choose branch automatically. CNR mode uses the standard ISA-based dispatching model while ensuring fixed cache sizes, deterministic reductions, and static scheduling |
MKL_CBWR_COMPATIBLE |
3 |
Intel® Streaming SIMD Extensions 2 (Intel® SSE2) without rcpps/rsqrtps instructions |
MKL_CBWR_SSE2 |
4 |
Intel SSE2 |
MKL_CBWR_SSE3 |
5 |
DEPRECATED. Intel® Streaming SIMD Extensions 3 (Intel® SSE3). This setting is kept for backward compatibility and is equivalent to MKL_CBWR_SSE2. |
MKL_CBWR_SSSE3 |
6 |
Supplemental Streaming SIMD Extensions 3 (SSSE3) |
MKL_CBWR_SSE4_1 |
7 |
Intel® Streaming SIMD Extensions 4-1 (SSE4-1) |
MKL_CBWR_SSE4_2 |
8 |
Intel® Streaming SIMD Extensions 4-2 (SSE4-2) |
MKL_CBWR_AVX |
9 |
Intel® Advanced Vector Extensions (Intel® AVX) |
MKL_CBWR_AVX2 |
10 |
Intel® Advanced Vector Extensions 2 (Intel® AVX2) |
MKL_CBWR_AVX512_MIC |
11 |
DEPRECATED. Intel® Advanced Vector Extensions 512 (Intel® AVX-512) on Intel® Xeon Phi™ processors. This setting is kept for backward compatibility and is equivalent to MKL_CBWR_AVX2. |
MKL_CBWR_AVX512 |
12 |
Intel AVX-512 on Intel® Xeon® processors |
MKL_CBWR_AVX512_MIC_E1 |
13 |
DEPRECATED. Intel® Advanced Vector Extensions 512 (Intel® AVX-512) for Intel® Many Integrated Core Architecture (Intel® MIC Architecture) with support of AVX512_4FMAPS and AVX512_4VNNIW instruction groups enabled processors. This setting is kept for backward compatibility and is equivalent to MKL_CBWR_AVX2. |
MKL_CBWR_AVX512_E1 |
14 |
Intel® Advanced Vector Extensions 512 (Intel® AVX-512) with support of Vector Neural Network Instructions enabled processors |
| CNR Flags | ||
MKL_CBWR_STRICT |
65536 or 0x10000 |
Strict CNR mode enabled. See Reproducibility Conditions for more information. |
When specifying the CNR branch with the named constants, be aware of the following:
Reproducible results are provided under Reproducibility Conditions.
Settings other than MKL_CBWR_AUTO or MKL_CBWR_COMPATIBLE are available only for Intel processors.
Intel and Intel compatible CPUs have a few instructions, such as approximation instructions rcpps/rsqrtps, that may return different results. Setting the branch to MKL_CBWR_COMPATIBLEensures that Intel® oneAPI Math Kernel Library does not use these instructions and forces a single Intel SSE2-only code path to be executed.
Product and Performance Information |
|---|
Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex. Notice revision #20201201 |