[petsc-users] MPI+OpenMP+MKL

[Astor Piaz]

I'm sorry I meant OpenMP threads are able to spawn MKL processes

On Fri, Apr 7, 2023 at 8:29 PM Dave May <dave.mayhem23 at gmail.com> wrote:

>
>
> On Fri 7. Apr 2023 at 07:06, Astor Piaz <appiazzolla at gmail.com> wrote:
>
>> Hello petsc-users,
>> I am trying to use a code that is parallelized with a combination of
>> OpenMP and MKL parallelisms, where OpenMP threads are able to spawn MPI
>> processes.
>>
>
> Is this really the correct way to go?
>
>
> Would it not be more suitable (or simpler) to run your application on an
>  MPI sub communicator which maps one rank to say one compute node, and then
> within each rank of the sub comm you utilize your threaded OpenMP / MKL
> code using as many physical threads as there are cores/ node  (and or hyper
> threads if that’s is effective for you)?
>
> Thanks,
> Dave
>
> I have carefully scheduled the processes such that the right amount is
>> launched, at the right time.
>> When trying to use my code inside a MatShell (for later use in an FGMRES
>> KSPSolver), MKL processes are not being used.
>>
>> I am sorry if this has been asked before.
>> What configuration should I use in order to profit from MPI+OpenMP+MKL
>> parallelism?
>>
>> Thank you!
>> --
>> Astor
>>
>
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