Messages in this thread |  | | | Date | Mon, 28 Jan 2008 17:57:49 +0100 | | From | "Guillaume Chazarain" <> | | Subject | Re: High wake up latencies with FAIR_USER_SCHED |
Hi Srivatsa,
On Jan 28, 2008 3:31 AM, Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> wrote:
> Given that sysctl_sched_wakeup_granularity is set to 10ms by default,
> this doesn't sound abnormal.
Indeed, by lowering sched_wakeup_granularity I get much better
latencies, but lowering sched_latency seems to be more effective.
> NEW_FAIR_SLEEPERS feature gives credit for sleeping only to tasks and
> not group-level entities. With the patch attached, I could see that wakeup
> latencies with FAIR_USER_SCHED are restored to the same level as
> !FAIR_USER_SCHED.
Thanks for the patch, it works perfectly.
> However I am not sure whether that is the way to go. We want to let one group of
> tasks running as much as possible until the fairness/wakeup-latency threshold is
> exceeded. If someone does want better wakeup latencies between groups too, they
> can always tune sysctl_sched_wakeup_granularity.
Having an inconsistency here between FAIR_USER_SCHED and
!FAIR_USER_SCHED sounds strange, but Ingo took the patch, so I'm happy
:-)
Thanks for the replies.
--
Guillaume
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