Messages in this thread | | | Date | Mon, 19 Nov 2007 22:11:42 +0100 | From | Pavel Machek <> | Subject | Re: nohz and strange sleep latencies |
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Hi!
> > On unloaded x60 system, 2.6.24-rc3 (tainted-pavel-so if someone can > > reproduce it, it would be helpful): > > > > pavel@amd:~$ while true; do time sleep 0.01; done > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 30.71%CPU > > 0.00user 0.00system 0.02 (0m0.024s) elapsed 8.36%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.53%CPU > > 0.00user 0.00system 0.02 (0m0.026s) elapsed 7.75%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.34%CPU > > 0.00user 0.00system 0.20 (0m0.207s) elapsed 1.45%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.59%CPU > > 0.00user 0.00system 0.23 (0m0.230s) elapsed 1.30%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.61%CPU > > 0.00user 0.00system 0.20 (0m0.201s) elapsed 1.48%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.50%CPU > > 0.00user 0.00system 0.19 (0m0.190s) elapsed 1.05%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.37%CPU > > 0.00user 0.00system 0.04 (0m0.049s) elapsed 4.09%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.35%CPU > > 0.00user 0.00system 0.01 (0m0.017s) elapsed 11.89%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.38%CPU > > 0.00user 0.00system 0.08 (0m0.081s) elapsed 3.71%CPU > > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.33%CPU > > 0.00user 0.00system 0.01 (0m0.019s) elapsed 15.92%CPU > > > > nohz=off helps a lot. while true; do time sleep 0.0; done does not > > have unexpected latencies. > > does hpet=disable on the boot line also help? (without nohz=off)
hpet-disable helps.. a bit. 200msec latencies are gone. (What is used for wakeups in this case?)
pavel@amd:~$ while true; do time sleep 0.01; done 0.00user 0.00system 0.01 (0m0.013s) elapsed 22.96%CPU 0.00user 0.00system 0.01 (0m0.018s) elapsed 11.05%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.54%CPU 0.00user 0.00system 0.03 (0m0.037s) elapsed 8.05%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.34%CPU 0.00user 0.00system 0.03 (0m0.037s) elapsed 8.14%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.33%CPU 0.00user 0.00system 0.03 (0m0.037s) elapsed 8.16%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.30%CPU 0.00user 0.00system 0.03 (0m0.037s) elapsed 5.47%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.25%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.54%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.56%CPU 0.00user 0.00system 0.03 (0m0.036s) elapsed 5.49%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.35%CPU 0.00user 0.00system 0.03 (0m0.037s) elapsed 8.14%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.35%CPU 0.00user 0.00system 0.03 (0m0.037s) elapsed 8.14%CPU 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.34%CPU 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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