Messages in this thread | | | Subject | Re: [git pull] scheduler changes for v2.6.26 | From | Peter Zijlstra <> | Date | Tue, 22 Apr 2008 11:59:23 +0200 |
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On Tue, 2008-04-22 at 10:59 +0200, Ingo Molnar wrote: > * Mike Galbraith <efault@gmx.de> wrote: > > > > the 700-800 msecs of delays you see are very "brutal" so there must > > > be something fundamentally wrong going on here. > > > > I'm seeing latency hits with 26.git, whereas 25 is hit free. > > ok. I think what happens is that your broken sched-clock hid the real > breakage. Lets try fix the real breakage now. > > I've uploaded a new sched-devel.git that is against very latest -git, > could you try ftrace (with a sufficiently large > /debug/tracing/tracing_max_entries value) - perhaps the > worst-case-wakeup-latency tracer shows large latencies? If not, then > maybe the sched_switch tracer gives a better insight into what's > happening? > > > Erm, should my Q6600 emit such? > > on nohz it could happen - and fixed in -git. Patch looked too dangerous > for late-2.6.25 to merge.
Also, it only happens when the cpu has idle time; and that typically happens when its well,. idle - so not much to schedule wrong.
That said; yes there are boundary effect that could make it show up.
> > On 26.git, I get numbers like yours, but with occasional dips down to > > ~700, though the latency hits don't _seem_ to be synchronous with > > watch-rq-clock.sh glitchies. > > hm, the dips shouldnt be happening normally.
Agreed, those ought to be gone.. Guillaume do you see any holes in the current rq clock code?
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