Does enabling hyperthreading or not have any effect on MKL performance?

[Tony_Garratt]

Does enabling hyperthreading or not have any effect on the performance (speed) of MKL, in particular BLAS and LAPACK routines?

[Shane_S_Intel]

Quoting - Tony Garratt

Does enabling hyperthreading or not have any effect on the performance (speed) of MKL, in particular BLAS and LAPACK routines?

Hi Tony, we typically recommend against enabling HT because it has a negative effect on BLAS/LAPACK performance. See the knowledge base article: http://software.intel.com/en-us/articles/setting-thread-affinity-on-smt-or-ht-enabled-systems/.
-Shane

[TimP]

Quoting - Shane Story (Intel)

Hi Tony, we typically recommend against enabling HT because it has a negative effect on BLAS/LAPACK performance. See the knowledge base article: http://software.intel.com/en-us/articles/setting-thread-affinity-on-smt-or-ht-enabled-systems/.
-Shane

set KMP_AFFINITY= physical[,0,verbose]
and
OMP_NUM_THREADS <= number of available cores
if you require run with HT enabled and have a recent libiomp which supports this KMP option. As Shane suggests, an application such as MKL which can keep the FPU and other resources busy will not benefit from sharing the important resources among threads.
Shane, Thanks for the KB. It should be required reading for management and marketing.

[Tony_Garratt]

Thank you!