[Beowulf] Not all cores are created equal

[Chris Samuel]

----- "Nifty Tom Mitchell" <niftyompi at niftyegg.com> wrote:

> On Wed, Dec 24, 2008 at 09:03:38PM +1100, Chris Samuel wrote:
>
> > I contemplated doing this on our Barcelona cluster, but
> > sacrificing 1 core in 8 was a bit too much of a high price
> > to pay.  But people with higher core counts per node might
> > find it attractive.
> 
> This seems like a be a benchmark decision based on application 
> load and 'implied IO+OS' loading as well as the ability to
> localize the IO+OS activity to the sacrificed CPU core.

I'll leave that to sites that have a benchmarkable and
characterisable workload.  :-)  We've got over 600 random
users running random code (some very random indeed [1])
that covers all categories from self-written, through open
source to commercial apps.

cheers,
Chris

[1] - including a commercial code that segfaults in one
particular program in libmsxml.so - yes, that appears to
be a 3rd party implementation of the M$ XML library on Linux.
When reported they claimed it was because we were running
CentOS5 not RHEL4.  Can't reproduce on RHEL4 because it
crashes *before* that point on that distro.  Gah.

-- 
Christopher Samuel - (03) 9925 4751 - Systems Manager
 The Victorian Partnership for Advanced Computing
 P.O. Box 201, Carlton South, VIC 3053, Australia
VPAC is a not-for-profit Registered Research Agency