Messages in this thread | | | From | Al Boldi <> | Subject | Re: CFS review | Date | Mon, 27 Aug 2007 17:46:47 +0300 |
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Ingo Molnar wrote: > * Al Boldi <a1426z@gawab.com> wrote: > > > could you send the exact patch that shows what you did? > > > > On 2.6.22.5-v20.3 (not v20.4): > > > > 340- curr->delta_exec += delta_exec; > > 341- > > 342- if (unlikely(curr->delta_exec > sysctl_sched_stat_granularity)) > > { 343:// __update_curr(cfs_rq, curr); > > 344- curr->delta_exec = 0; > > 345- } > > 346- curr->exec_start = rq_of(cfs_rq)->clock; > > ouch - this produces a really broken scheduler - with this we dont do > any run-time accounting (!).
Of course it's broken, and it's not meant as a fix, but this change allows you to see the amount of overhead as well as any miscalculations __update_curr incurs.
In terms of overhead, __update_curr incurs ~3x slowdown, and in terms of run-time accounting it exhibits a ~10sec task-startup miscalculation.
> Could you try the patch below instead, does this make 3x glxgears smooth > again? (if yes, could you send me your Signed-off-by line as well.)
The task-startup stalling is still there for ~10sec.
Can you see the problem on your machine?
Thanks!
-- Al
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