Re: [starpu-devel] Creating thread partitions

[Doru Adrian Thom Popovici <dtpopovici@lbl.gov>]

Hello Samuel.

Hmmm. So I tried that with a simple code that just spawned t threads that do an operation. I have the omp parallel for exposed. That works well and I see all the threads.

But when I try to add a library call to graphblas for example it seems like that entire parallel region only runs with one thread...

I am trying to identify where my mistake is... Is is from starpu or from graphblas.

Thank you for the your fast response.

Doru 

Email sent from the phone so please excuse the typos.

On Wed, Nov 29, 2023, 01:55 Samuel Thibault <samuel.thibault@inria.fr> wrote:

Hello,

Doru Adrian Thom Popovici, le mar. 28 nov. 2023 23:52:59 -0800, a ecrit:
> I was reading the documentation, and in there it was said that if a context is
> created without a scheduling policy, then that context basically is a parallel
> worker.
>
> Based on my understanding, I got all the cpus on the system. From there I
> create some sub-contexts that do not have any scheduling policy. Basically I
> partition the CPUs in p groups. Each group having t cpus.
>
> Then I create a master context that has a policy. 
>
> If I submit tasks to the big_sched_ctx context, each task is transmitted to the
> sub-contexts? Is this  assumption correct? I just want p parallel workers with
> t threads each. I hope I got the documentation correctly.

That is the idea, yes. That simplifies managing parallel tasks: you
just statically partition the machine and the scheduler only sees
more-powerful "workers".

Samuel