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Subject: [hwloc-users] hwloc on Blue Gene/Q?
From: Erik Schnetter (schnetter_at_[hidden])
Date: 2013-01-08 12:06:48


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]>
http://www.perimeterinstitute.ca/personal/eschnetter/