Messages in this thread | | | Date | Tue, 13 May 2008 21:04:05 +0200 | From | "Vegard Nossum" <> | Subject | Re: Rescheduling interrupts |
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On Tue, May 13, 2008 at 8:03 PM, Vegard Nossum <vegard.nossum@gmail.com> wrote: > Hi, > > > On Tue, Jan 22, 2008 at 6:05 PM, Ingo Molnar <mingo@elte.hu> wrote: > > > > * S.Çağlar Onur <caglar@pardus.org.tr> wrote: > > > > > > > > My theory is that for whatever reason we get "repeat" IPIs: multiple > > > > reschedule IPIs although the other CPU only initiated one. > > > > > > Ok, please see http://cekirdek.pardus.org.tr/~caglar/dmesg.3rd :) > > > > hm, the IPI sending and receiving is nicely paired up: > > > > [ 625.795008] IPI (@smp_reschedule_interrupt) from task swapper:0 on CPU#1: > > [ 625.795223] IPI (@native_smp_send_reschedule) from task amarokapp:2882 on CPU#1: > > > > amarokapp does wake up threads every 20 microseconds - that could > > explain it. It's probably Xorg running on one core, amarokapp on the > > other core. That's already 100 reschedules/sec. > > Was this IPI thing ever resolved/fixed? I'm seeing the exact same > thing on my newest Fedora 8 kernel (2.6.24.5-85.fc8) now: > > 33.3% (334.0) <kernel IPI> : Rescheduling interrupts > > And I know for sure that this did not show up a couple of months back. > > If the cause of this is known, please let me know about it. If it > isn't, I will start a bisect run now :-)
Ok -- just a confirmation. I have this on v2.6.26-rc1:
Running only init=/bin/sh (from busybox) and powertop shows: kernel IPI : Rescheduling interrupts
completely idle box (except powertop): 1 wakeups/sec one busy-loop[1]: 2 wakeups/sec two busy-loops: 500 wakeups/sec
So it seems like a real bug to me.
Vegard
[1]: while true; do echo hi; done
-- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036
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