Sleeping task has no utiliation, when they were bursty waked up, the zero utilization make scheduler out of balance, like aim7 benchmark.
rq->avg_idle is 'to used to accommodate bursty loads in a dirt simple dirt cheap manner' -- Mike Galbraith. With this cheap and smart bursty indicator, we can find the wake up burst, and use nr_running as instant utilization in this scenario. For other scenarios, we still use the precise CPU utilization to judage if a domain is eligible for power scheduling. Thanks for Mike Galbraith's idea! Thanks for Namhyung's suggestion to compact the burst into max_rq_util()! Signed-off-by: Alex Shi <alex....@intel.com> --- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f610313..a729939 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3363,6 +3363,10 @@ static unsigned int max_rq_util(int cpu) unsigned int cfs_util; unsigned int nr_running; + /* use nr_running as instant utilization for burst cpu */ + if (cpu_rq(cpu)->avg_idle < sysctl_sched_burst_threshold) + return rq->nr_running * FULL_UTIL; + /* yield cfs utilization to rt's, if total utilization > 100% */ cfs_util = min(rq->util, (unsigned int)(FULL_UTIL - rt_util)); -- 1.7.12 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/