Messages in this thread | | | Date | Tue, 20 Jan 2009 14:37:26 +0200 | From | Avi Kivity <> | Subject | Re: [Bug #12465] KVM guests stalling on 2.6.28 (bisected) |
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Ingo Molnar wrote: > * Kevin Shanahan <kmshanah@ucwb.org.au> wrote: > > >> On Mon, 2009-01-19 at 22:45 +0100, Rafael J. Wysocki wrote: >> >>> This message has been generated automatically as a part of a report >>> of regressions introduced between 2.6.27 and 2.6.28. >>> >>> The following bug entry is on the current list of known regressions >>> introduced between 2.6.27 and 2.6.28. Please verify if it still should >>> be listed and let me know (either way). >>> >>> >>> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=12465 >>> Subject : KVM guests stalling on 2.6.28 (bisected) >>> Submitter : Kevin Shanahan <kmshanah@ucwb.org.au> >>> Date : 2009-01-17 03:37 (3 days old) >>> >> Yes, please keep this on the list. >> > > This only seems to occur under KVM, right? I.e. you tested it with -no-kvm > and the problem went away, correct? > > 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. > >
Not necessarily. -no-kvm runs with only one thread, compared to kvm that runs with 1 + nr_cpus threads.
> Avi, can you reproduce these latencies?
No.
> A possibly theory would be some > sort of guest wakeup problem/race triggered by a shift in > preemption/scheduling patterns. Or something related to preempt-notifiers > (which KVM is using). A genuine scheduler bug is in the cards too, but the > KVM-only angle of this bug gives it a low probability. >
Can we trace task wakeups somehow? (latency between wakeup and actually running).
-- error compiling committee.c: too many arguments to function
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