Anyone have information on latest LSU beowulf?

Patrick Geoffray patrick at
Wed Oct 9 09:39:03 PDT 2002

On Wed, 2002-10-09 at 12:07, Craig Tierney wrote:

> This says that NB=40 is good for the PIII which has a larger
> L1 cache than a P4 (16k data vs. 8k).  NB should be a multiple
> of 32 for the P4.  I would like to try it out on a PIII, I would
> think that 44 is a better value based on cache size.  I tried
> all these tricks on an Alpha was 16k L1 cache and found 88 (44*2)
> best.

Which value is used by ATLAS ? Stick with it. It may be 40 or 32 or
whatever, but it will be the granularity of DGEMM used in HPL.
If 32 is the block size used by ATLAS, try ro tun with NB as 32, 64, 96
and 128.

|   Patrick Geoffray, Ph.D.      patrick at 
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