[Beowulf] running the Linpak -HPL benchmark.

Gus Correa gus at ldeo.columbia.edu
Thu Jan 14 17:25:17 PST 2010

Hi Rahul

It is a bit involved, but not very difficult to setup HPL.

First get the Goto BLAS/LAPACK from TACC:
Install it using the Gnu compilers.

Then get HPL from Netlib:

Tweak with the Makefile to point to your mpi wrappers,
and to the Goto Library.
Build HPL.

Read the TUNING file that comes with HPL.
It has important information about the input parameters.
The main ones are N, and P,Q.

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).

I hope this helps,
Gus Correa
Gustavo Correa
Lamont-Doherty Earth Observatory - Columbia University
Palisades, NY, 10964-8000 - USA

Rahul Nabar wrote:
> I've never had a cluster large enough to matter but I was thinking of
> running the Linpak-HPL benchmark (from the top500 site) just out of
> curiosity of knowing my actual teraflops. For one, it would tell me
> how much my Rmax/Rpeak so that I know how non-optimal my network and
> other infrastructure was.
> Question: How difficult it is getting that benchmark to run? Was eager
> to know of opinions from sys-admins who've "been there, done that".
>  If it was a horrendously difficult process I might just skip it. Some
> their tuning sections were scary.
> Are there any good pointers on tuning parameter selection or ready
> made makefiles? I had a Intel Nehalem processor and a regular Gigabit
> network.

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