Messages in this thread | | | Date | Tue, 20 Jan 2009 13:56:52 +0100 | From | Ingo Molnar <> | Subject | Re: [Bug #12465] KVM guests stalling on 2.6.28 (bisected) |
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* Kevin Shanahan <kmshanah@ucwb.org.au> wrote:
> > This suggests some sort of KVM-specific problem. Scheduler latencies > > in the seconds that occur under normal load situations are noticed and > > reported quickly - and there are no such open regressions currently. > > It at least suggests a problem with interaction between the scheduler > and kvm, otherwise reverting that scheduler patch wouldn't have made the > regression go away.
the scheduler affects almost everything, so almost by definition a scheduler change can tickle a race or other timing bug in just about any code - and reverting that change in the scheduler can make the bug go away. But yes, it could also be a genuine scheduler bug - that is always a possibility.
Could you please run a cfs-debug-info.sh session on a CONFIG_SCHED_DEBUG=y and CONFIG_SCHEDSTATS=y kernel, while you are experiencing those latencies:
http://people.redhat.com/mingo/cfs-scheduler/tools/cfs-debug-info.sh
and post that (relatively large) somewhere, or send it as a reply after bzip2 -9 compressing it? It will include a lot of information about the delays your tasks are experiencing.
Ingo
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