unset bli_thread_set_num_threads

[istispl]

Calling bli_thread_set_num_threads(n) takes precedence over omp_set_num_threads(m).
Is there a way to unset or reset the BLIS threading at the initial state where it takes into account the OpenMP thread settings - and follow the number set by subsequent omp_set_num_threads?

Something like calling bli_thread_set_num_threads(0) could mean to follow OpenMP of threads?

MKL has a similar method where calling MKL_Domain_Set_Num_Threads(0,MKL_DOMAIN_ALL) would use the number of threads from the OpenMP library.

Thanks

[kvaragan]

Can you use only omp_set_num_threads() instead of bli_thread_set_num_threads() ?

[edwsmyth]

Hi @istispl, apologies for the delay in updating this ticket. There is functionality in BLIS to do this. The API is

bli_thread_reset();

This has been in upstream BLIS since commit 6dcf766 (pre-1.0 release), and in AOCL BLIS since our 5.2 release (note the version numbering is completely different).

There are currently some differences in how threading is handled in upstream vs AOCL BLIS, but the essence of this API is that it will restore the BLIS threading settings to what it was when the program first started, i.e. it will clear any settings made by calls to bli_thread_set_num_threads() or bli_thread_set_ways(). This will allow OpenMP thread count settings to again be in force, unless the BLIS_NUM_THREADS environment variable was set before the program was run.