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Subject: Re: [hwloc-users] hwloc on Blue Gene/Q?
From: Brice Goglin (Brice.Goglin_at_[hidden])
Date: 2013-02-09 17:46:12

The new "bgq" branch now contains proper topology for BG/Q nodes
(including cores and caches, except the prefetching cache) as well as
support for set/get binding of the current thread or of another thread.
No process-wide binding since I don't know how to iterate over all
threads of a process.

A tarball is available at:
(this is our new regression testing tool, I hope the tarball won't
disappear too soon)

I don't expect a lot more features so this branch will likely go into
trunk very soon. But if you can look at it, that'll be great.


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]>>
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