Messages in this thread | | | Date | Fri, 23 Nov 2007 13:22:54 +0100 | From | Pavel Machek <> | Subject | Re: nohz and strange sleep latencies |
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Hi!
> > > but perhaps somehow we miss this fact and fail to turn off the lapic > > > clockevents drivers? > > > > Ok, I guess I'm lost. If I offline second CPU, I immediately get > > 1000Hz timer tick... is that expected? > > Hmm. No. I have no idea why this is happening. > > 34196 total events, 55.083 events/sec > echo 0 >/sys/devices/system/cpu/cpu1/online > 36073 total events, 54.679 events/sec
Strange.
> > I'm trying to decide when system is idle (lets say that means "no user > > task is scheduled to wakeup within 10 seconds)... I added some > > instrumentation to nohz subsystem, but it does not behave like I'd > > expect: even if I run "while true; do sleep .01; done" loop, I see > > nohz preparing for 5 seconds sleep... while it seems obvious that it > > can only be 10msec sleep, and with max_cstate=1, it works that > > way... Plus, nte->start_pid seems to contain some random numbers :-(. > > > > What am I doing wrong? > > > > (Patch for illustration, I can generate full diff against vanilla, > > but...) > > Just to make sure what we are hunting: Do you have the same problem > with an non-pavel-tainted 2.6.24-rc3 ?
The strange sleep latencies were definitely there, I'll check for "offline cpu and get 1000 interrupts", too. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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