Messages in this thread | | | Date | Wed, 27 Oct 2010 21:42:37 +0200 | From | Markus Trippelsdorf <> | Subject | Re: [bisected] Clocksource tsc unstable git |
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On Wed, Oct 27, 2010 at 09:36:55PM +0200, Peter Zijlstra wrote: > On Wed, 2010-10-27 at 20:26 +0200, markus@trippelsdorf.de wrote: > > > > 34f971f6f7988be4d014eec3e3526bee6d007ffa is the first bad commit > > commit 34f971f6f7988be4d014eec3e3526bee6d007ffa > > Author: Peter Zijlstra <a.p.zijlstra@chello.nl> > > Date: Wed Sep 22 13:53:15 2010 +0200 > > > > sched: Create special class for stop/migrate work > > > > In order to separate the stop/migrate work thread from the SCHED_FIFO > > implementation, create a special class for it that is of higher priority than > > SCHED_FIFO itself. > > > > This currently solves a problem where cpu-hotplug consumes so much cpu-time > > that the SCHED_FIFO class gets throttled, but has the bandwidth replenishment > > timer pending on the now dead cpu. > > > > It is also required for when we add the planned deadline scheduling class above > > SCHED_FIFO, as the stop/migrate thread still needs to transcent those tasks. > > > > Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com> > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > > LKML-Reference: <1285165776.2275.1022.camel@laptop> > > Signed-off-by: Ingo Molnar <mingo@elte.hu> > > > > Reverting the commit solves the kvm hang issue. > > (If this issue is related to my original tsc problem is of course open for > > debate, but I have a strong hunch it is.) > > Too weird,.. what does the hang look like? > > Can you generate a sysrq-t dump? The thing I'm looking for is the > migration/# thread being runnable but not being current. > > How can I reproduce this?
It's quite easy to reproduce on my setup. I simply run:
qemu-kvm -net nic,vlan=0,model=virtio -net user -drive file=ubuntu,if=virtio,boot=on -smp 2 -m 512
and then move the mousepointer in circles in the qemu window. It will stop and freeze after a few seconds. -- Markus
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