[Beowulf] bizarre scaling behavior on a Nehalem

Rahul Nabar rpnabar at gmail.com
Wed Aug 12 10:56:11 PDT 2009

On Wed, Aug 12, 2009 at 11:32 AM, Craig Tierney<Craig.Tierney at noaa.gov> wrote:
> What do you mean normally?  I am running Centos 5.3 with 2.6.18-128.2.1
> right now on a 448 node Nehalem cluster.  I am so far happy with how things work.
> The original Centos 5.3 kernel, 2.6.18-128.1.10 had bugs in Nelahem support
> where nodes would just start randomly run slow.  Upgrading the kernel
> fixed that.  But that performance problem was either all or none, I don't recall
> it exhibiting itself in the way that Rahul described.

For me it shows:

Linux version 2.6.18-128.el5 (mockbuild at builder10.centos.org)

I am a bit confused with the numbering scheme, now. Is this older or
newer than Craigs? You are right Craig, I haven't noticed any random
slowdowns but my data is statistically sparse. I only have a single
Nehalem+CentOS test node right now.


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