on 06/07/2011 21:00 Steve Kargl said the following: > On Wed, Jul 06, 2011 at 05:05:41PM +0000, Poul-Henning Kamp wrote: >> In message <20110706170132.ga68...@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 ;-)
I think that Poul-Henning was speaking in the vein of the subject line where I/O is somehow involved. I admit I would also love to hear more details in more technical terms (without lemmings and cliffs) :-) > 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. Your issue seems to be about a specific case of purely CPU-bound loads. It is very relevant to ULE, but perhaps not to this particular thread. >> 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 would love to hear more about this. A link to a past discussion, if any, would suffice. -- Andriy Gapon _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
