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Subject: Re: [hwloc-users] hwloc on Blue Gene/Q?
From: Brice Goglin (Brice.Goglin_at_[hidden])
Date: 2013-01-08 12:10:07


Hello Erik,
We need specific BGQ binding support, the binding API is different. Also
we don't properly detect the 16 4-way cores properly, we only only 64
identical PUs.
I am supposed to get a BGQ account in the near future so I hope I will
have everything working in v1.7.
Stay tuned
Brice

Le 08/01/2013 18:06, Erik Schnetter a écrit :
> I am trying to use hwloc on a Blue Gene/Q. Building and installing
> worked fine, and it reports the system configuration fine as well
> (i.e. it shows all PUs). However, when I try to inquire the
> thread/core bindings, hwloc crashes with an error in libc's free().
> This is both with 1.6 and 1.6.1rc1.
>
> The error occurs apparently in CPU_FREE called from
> hwloc_linux_find_kernel_nr_cpus.
>
> Does this ring a bell with anyone? I know this is not enough
> information to debug things, but do you have any pointers for things
> to look at?
>
> I remember reading somewhere that the last bit in a cpu_set_t cannot
> be used. A Blue Gene/Q has 64 PUs, and may be using 64-bit integers to
> hold cpu_set_t data. Could this be an issue?
>
> My goal is to examine and experiment with thread/core bindings with
> OpenMP to improve performance.
>
> -erik
>
> --
> Erik Schnetter <schnetter_at_[hidden] <mailto:schnetter_at_[hidden]>>
> http://www.perimeterinstitute.ca/personal/eschnetter/
>
>
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