Re: [git] CFS-devel, latest code

From: Ingo Molnar
Date: Tue Sep 25 2007 - 05:13:50 EST

* Mike Galbraith <efault@xxxxxx> wrote:

> > sched_debug (attached) is.. strange.
> Disabling CONFIG_FAIR_GROUP_SCHED fixed both. [...]

heh. Evil plan to enable the group scheduler by default worked out as
planned! ;-) [guess how many container users would do ... interactivity
tests like you do??]

> [...] Latencies of up to 336ms hit me during the recompile (make -j3),
> with nothing else running. Since reboot, latencies are, so far, very
> very nice. [...]

'very very nice' == 'best ever' ? :-)

> [...] I'm leaving it disabled for now.

ok, i'm too seeing some sort of latency weirdness with
CONFIG_FAIR_GROUP_SCHED enabled, _if_ there's Xorg involved which runs
under root uid on my box - and hence gets 50% of all CPU time.

Srivatsa, any ideas? It could either be an accounting buglet (less
likely, seems like the group scheduling bits stick to the 50% splitup
nicely), or a preemption buglet. One potential preemption buglet would
be for the group scheduler to not properly preempt a running task when a
task from another uid is woken?

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