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Subject: Re: [hwloc-users] hwloc on Blue Gene/Q?
From: Erik Schnetter (schnetter_at_[hidden])
Date: 2013-02-15 15:12:45


Brice

Yepp, works for me as well. Thanks!

-erik

On Mon, Feb 11, 2013 at 2:51 AM, Brice Goglin <Brice.Goglin_at_[hidden]> wrote:

> Obviously, I should have mentioned that you must pass
> --host=powerpc64-bgq-linux to configure. I will add a FAQ about this.
>
> Brice
>
>
>
>
> Le 11/02/2013 01:52, Erik Schnetter a écrit :
>
> Brice
>
> I tried using this tarball. Things didn't work. (This particular run
> used 2 MPI processes with 32 OpenMP threads each.)
>
> In my application, I first output the topology in a tree structure. (I
> do this in my application instead of via one of hwloc's tools because I
> don't want to call out to shell code.) Then I output thread bindings, then
> modify the thread bindings, then output them again.
>
> (1) The topology I find consists of 32 PUs and nothing else. I would
> have expected to find two cache levels, 16 cores, and 64 PUs.
>
> (2) When outputting the thread bindings, I received a segfault. The
> lightweight core file says this was signal 6 (SIGABRT) in a routine called
> ".raise".
>
> I'd be happy to help debug this. How?
>
> -erik
>
>
>
>
> On Sat, Feb 9, 2013 at 5:46 PM, Brice Goglin <Brice.Goglin_at_[hidden]>wrote:
>
>> 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:
>>
>> https://ci.inria.fr/hwloc/job/hwloc-zcustom-tarball/lastSuccessfulBuild/artifact/hwloc-1.7a1r5312.tar.gz
>> (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.
>>
>>
>> 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]>
>> http://www.perimeterinstitute.ca/personal/eschnetter/
>>
>>
>> _______________________________________________
>> hwloc-users mailing listhwloc-users_at_[hidden]http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users
>>
>>
>>
>
>
> --
> Erik Schnetter <schnetter_at_[hidden]>
> http://www.perimeterinstitute.ca/personal/eschnetter/
>
>
>

-- 
Erik Schnetter <schnetter_at_[hidden]>
http://www.perimeterinstitute.ca/personal/eschnetter/