[Beowulf] running the Linpak -HPL benchmark.

Rahul Nabar rpnabar at gmail.com
Sat Jan 16 22:02:35 EST 2010


On Thu, Jan 14, 2010 at 7:25 PM, Gus Correa <gus at ldeo.columbia.edu> wrote:

>
> First, to test, run HPL in a single node or a few nodes,
> using small values of N, say 1000 to 20000.
>
> The maximum value of N can be approximated by
> Nmax = sqrt(0.8*Total_RAM_on_ALL_nodes_in_bytes/8).
> This uses all the RAM, but doesn't get into memory paging.
>
> Then run HPL on the whole cluster with the Nmax above.
> Nmax pushes the envelope, and is where your
> best performance (Rmax/Rpeak) is likely to be reached.
> Try several P/Q combinations for Nmax (see the TUNING file).
>

Thanks Gus! That helps a lot. I have Linpak running now on just a
single server and am trying to tune and hit the Rpeak.

I'm getting 62 Gflops but I think my peak has to be around 72 (2.26
GHz 8 cores Nehalem). On a single server test do you manage to hit the
theoretical peak?What's a good Rmax / Rpeak to shoot for while tuning?

Once I am confident I'm well tuned on one server I'll try and extend
it to the whole cluster.

-- 
Rahul
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