[petsc-users] strange PETSc/KSP GMRES timings for MPI+OMP configuration on KNLs

[Satish Balay]

MPI=16 OMP=1 time=45.62.

This timing [without OpenMP] looks out of place. Perhaps something
else [wierd MPI behavior?] is going on here..

Satish

On Fri, 16 Jun 2017, Damian Kaliszan wrote:

> Hi,
> 
> For  several  days  I've been trying to figure out what is going wrong
> with my python app timings solving Ax=b with KSP (GMRES) solver when trying to run on Intel's KNL 7210/7230.
> 
> I  downsized  the  problem  to  1000x1000 A matrix and a single node and
> observed the following:
> 
> 
> I'm attaching 2 extreme timings where configurations differ only by 1 OMP thread (64MPI/1 OMP vs 64/2 OMPs),
> 23321 vs 23325 slurm task ids.
> 
> Any help will be appreciated....
> 
> Best,
> Damian
>