On Wed, Jul 06, 2011 at 05:05:41PM +0000, Poul-Henning Kamp wrote: > In message <20110706170132.GA68775_at_troutmask.apl.washington.edu>, Steve Kargl w > rites: > > >I periodically ran the same type test in the 2008 post over the > >last three years. Nothing has changed. I even set up an account > >on one node in my cluster for jeffr to use. He was too busy to > >investigate at that time. > > Isn't this just the lemming-syncer hurling every dirty block over > the cliff at the same time ? I don't know the answer. Of course, having no experience in processing scheduling, I don't understand the question either ;-) AFAICT, it is a cpu affinity issue. If I launch n+1 MPI images on a system with n cpus/cores, then 2 (and sometimes 3) images are stuck on a cpu and those 2 (or 3) images ping-pong on that cpu. I recall trying to use renice(8) to force some load balancing, but vaguely remember that it did not help. > To find out: Run gstat and keep and eye on the leftmost column > > The road map for fixing that has been known for years... I'll keep this in mind, the next time I upgrade the cluster. It's currently running a Feb 10th vintage kernel, and is under fairly heavy use at the moment. -- SteveReceived on Wed Jul 06 2011 - 16:00:02 UTC
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