Messages in this thread | | | Date | Fri, 02 Nov 2007 21:58:14 +0530 | From | Balbir Singh <> | Subject | Re: delayacct regression in 2.6.24 git |
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Ingo Molnar wrote: > * Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > >> Hi, Ingo, >> >> I missed commit 75d4ef16a6aa84f708188bada182315f80aab6fa >> "sched: fix delay accounting performance regression" >> >> Without these changes, I find that delay accounting does >> not work as expected, I see zeros in the field for virtual,delay >> and count(s). >> >> CPU count real total virtual total delay total >> 0 535861848 0 0 >> >> >> This breaks existing delay accounting behaviour. >> >> Am I missing something? > > delay accounting was causing context-switch slowdown because it called > sched_clock() explicitly - but indeed my fix to that is wrong ... > > how about reverting the change but also using rq->clock instead of > sched_clock()?
Hmm... I think that might work, I find that schedule() calls __update_rq_clock() which in turn calls sched_clock(), so it might be a worthwhile optimization.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL - 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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