[Beowulf] Performance characterising a HPC application

[Douglas Eadline]

> On Tue, Mar 20, 2007 at 01:03:58PM +0000, Mattijs Janssens wrote:
>
>> A non-intrusive test you could try is to replace your MPI (mpich) with a
>> lower-latency one. Scali or MPI/Gamma are just to name two. These can
>> lower
>> your latency down to 15muS or so.
>
> Anyone been able to make MPI/Gamma work with the Broadcoms in SunFire
> X2100 and X2100 M2 series?

You really need two networks for GAMMA as GAMMA turns off TCP
while in use. Not to difficult with today's GigE-full nodes.
Just need extra an extra switch.

>
> I just got a X2100 M2 machine in today. 4 GBit ports, though 2 of them
> nVidia.

I was able to get 17 usecond latency (netpipe TCP ) with the nvidia
links on these systems. Out of the box broadcom was about
40 useconds (netpipe TCP).

 --
 Doug


>
> --
> Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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-- 
Doug