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Subject: Re: [hwloc-users] Process and thread binding
From: Gabriele Fatigati (g.fatigati_at_[hidden])
Date: 2011-09-12 07:29:49


Hi Birce,

I'm so confused..

I'm binding MPI processes with set_cpu_bind and it works well. The problem
is when I try to bind process and threads.

It seem that thread process influence bind of main thread.

And from hwloc manual:

hwloc_set_cpubind()

Bind *current process* or thread on cpus given in bitmap set.

Why you are saying tha process bind is not possible? I'm using it and it
work well!

2011/9/12 Brice Goglin <Brice.Goglin_at_[hidden]>

> Le 12/09/2011 12:52, Gabriele Fatigati a écrit :
> > Dear hwloc users,
> >
> > I'm binding process in a NUMA node and also associated OpenMP threads.
> > I've noted that, if I bind execution of all on different cores in
> > the same NUMA node , it works well.
> >
> > If I bind process in NUMA node 0 for example, and thread on NUMA node
> > 1, the process is bound on NUMA node 1, and not 0.
> >
> > Why this? Thread binding influence bind of main process?
> >
>
> Hello Gabriele,
> At least on Linux, you cannot bind a process. When you ask hwloc to bind
> a process, it just binds all threads contained in this process. When you
> do get_cpubind on a process, it returns the logical OR of the binding of
> all threads.
> Brice
>
> _______________________________________________
> hwloc-users mailing list
> hwloc-users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users
>

-- 
Ing. Gabriele Fatigati
HPC specialist
SuperComputing Applications and Innovation Department
Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
www.cineca.it                    Tel:   +39 051 6171722
g.fatigati [AT] cineca.it