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Subject: Re: [OMPI users] Running OpenMPI on SGI Altix with 4096 cores : very poor performance
From: John Hearns (hearnsj_at_[hidden])
Date: 2011-01-07 05:27:33

On 6 January 2011 21:10, Gilbert Grosdidier <Gilbert.Grosdidier_at_[hidden]> wrote:
> Hi Jeff,
>  Where's located lstopo command on SuseLinux, please ?
> And/or hwloc-bind, which seems related to it ?

I was able to get hwloc to install quite easily on SuSE -
Configure it to install to /usr/local/bin

Actually, the topic of hyperthreading is interesting, and we should
discuss it please.
Hyperthreading is supposedly implemented better and 'properly' on
Nehalem - I would be interested to see some genuine
performance measurements with hyperthreading on/off on your machine Gilbert.

Also you don;t need to reboot and change BIOS settings - there was a
rather niofty technique on this list I think,
where you disable every second CPU in Linux - which has the same
effect as switching off hyperthreading.
Maybe you could try it?