Messages in this thread | | | Subject | Re: CPU scheduler weirdness? | From | Peter Zijlstra <> | Date | Wed, 19 Aug 2009 14:10:34 +0200 |
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On Wed, 2009-08-19 at 14:01 +0200, Marton Balint wrote: > On Wed, 19 Aug 2009, Peter Zijlstra wrote: > > On Tue, 2009-08-18 at 21:49 +0200, Marton Balint wrote: > > > >> In the meantime, I was able to create a tiny C program which always > >> succesfully reproduces the bug. It's basically an endless loop which does > >> not stop while the process is running on the last CPU core. The program > >> creates multiple instances of itself, to be able to keep all of the CPU > >> cores busy. After 1 second, the processes running on other than the last > >> CPU core die, the processes running on the last CPU core remain stuck > >> there... > >> > >> I tested it on my dual core system, if someone could test it on a quad > >> core and report back that would probably be useful. > >> > >> Usage: ./schedtest <number of CPU cores> > >> > >> And don't forget to kill the stuck processes after using the program! :) > > > > So what's the bug? Sure one task will stay on the cpu, and because there > > is no contention it doesn't get migrated, and therefore won't quit, > > how's that a problem? > > Problem is that more than one processes remain on that CPU core, and none > of them get migrated to other (idle) cores. I tested it with my E8400 > processor and 2.6.31-rc5-git3 kernel.
Only one remains here.. on a c2q running 2.6.31-rc6-tip
Do you have a .config handy?
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