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Subject: Re: [hwloc-users] Thread binding problem
From: Gabriele Fatigati (g.fatigati_at_[hidden])
Date: 2012-09-05 09:44:53


Hi,

I've noted that hwloc_set_area_membind_nodeset return -1 but errno is not
equal to EXDEV or ENOSYS. I supposed that these two case was the two unique
possibly.

>From the hwloc documentation:

-1 with errno set to ENOSYS if the action is not supported
-1 with errno set to EXDEV if the binding cannot be enforced

Any other binding failure reason? The memory available is enought.

2012/9/5 Brice Goglin <Brice.Goglin_at_[hidden]>

> Hello Gabriele,
>
> The only limit that I would think of is the available physical memory on
> each NUMA node (numactl -H will tell you how much of each NUMA node memory
> is still available).
> malloc usually only fails (it returns NULL?) when there no *virtual*
> memory anymore, that's different. If you don't allocate tons of terabytes
> of virtual memory, this shouldn't happen easily.
>
> Brice
>
>
>
>
> Le 05/09/2012 14:27, Gabriele Fatigati a écrit :
>
> Dear Hwloc users and developers,
>
>
> I'm using hwloc 1.4.1 on a multithreaded program in a Linux platform,
> where each thread bind many non contiguos pieces of a big matrix using in a
> very intensive way hwloc_set_area_membind_nodeset function:
>
> hwloc_set_area_membind_nodeset(topology, punt+offset, len, nodeset,
> HWLOC_MEMBIND_BIND, HWLOC_MEMBIND_THREAD | HWLOC_MEMBIND_MIGRATE);
>
> Binding seems works well, since the returned code from function is 0 for
> every calls.
>
> The problems is that after binding, a simple little new malloc fails,
> without any apparent reason.
>
> Disabling memory binding, the allocations works well. Is there any
> knows problem if hwloc_set_area_membind_nodeset is used intensively?
>
> Is there some operating system limit for memory pages binding?
>
> Thanks in advance.
>
> --
> 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
>
>
> _______________________________________________
> hwloc-users mailing listhwloc-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