Messages in this thread | | | Date | Wed, 19 Aug 2009 14:34:45 +0200 (CEST) | From | Marton Balint <> | Subject | Re: CPU scheduler weirdness? |
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On Wed, 19 Aug 2009, Peter Zijlstra wrote:
> 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? >
Yes it's in my original post:
http://marc.info/?l=linux-kernel&m=125012584709800&w=2
Regards, Marton
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