On Tue, Apr 07, 2009 at 01:40:13PM -0600, Ralph Castain wrote: > I would really suggest looking at George's note first as I think you > are chasing your tail here. It sounds like the most likely problem is > that OMPI thinks you are oversubscribed and is setting sched_yield > accordingly. which would fully account for these diffs. > > Note that the methods for setting sched yield are different between > the various releases, so something could be catching you here. If you > are sure you aren't oversubscribing, then set -mca mpi_yield_when_idle > 0 on your cmd line to override any internal settings. >
'-mca mpi_yield_when_idle 0' returns the performance of 1.3.1 to that of 1.2.9. In fact, 1.3.1 may be marginally better. A comparison can be see at http://troutmask.apl.washington.edu/~kargl/ompi_cmp_yield.jpg So, in what file is sched_yield set? -- Steve
