Re: High CPU load when machine is idle (related to PROBLEM: Unusually high load average when idle in 2.6.35, 2.6.35.1 and later)

Damien Wyart
2010-11-30T17:00:10Z

* Peter Zijlstra <peterz@infradead.org> [101129 12:38]:
> > Doesn't give wrong numbers like initial bug and tentative patches, but
> > feels a bit too slow when numbers go up and down. Correct values are
> > reached when waiting long enough, but it feels slow.

> > As I've tested many combinations, maybe this is an impression because
> > I do not remember about "normal" delays for the load to rise and fall,
> > but this still feels slow.

> You can test this by either booting with nohz=off, or builting with
> CONFIG_NO_HZ=n and then comparing the result, something like

> make O=defconfig clean; while sleep 10; do uptime >> load.log; done &
> make -j32 O=defconfig; kill %1

> And comparing the curves between the NO_HZ and !NO_HZ kernels.

In fact, timings were very similar between the two configurations, so
I guess my feelings were wrong... They were also similar with the next
version of the patch.

--
Damien Wyart