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This patch maximizes time slice accounting. A task which receives too much CPU time due to missing the timer interrupt will have the excess deducted from it's next slice. Signed-off-by: Mike Galbraith <efault@gmx.de> --- linux-2.6.16-mm2/kernel/sched.c-7.implement_throttle 2006-03-24 09:36:08.000000000 +0100 +++ linux-2.6.16-mm2/kernel/sched.c 2006-03-24 09:40:33.000000000 +0100 @@ -2966,13 +2966,28 @@ static void refresh_timeslice(task_t *p) unsigned int slice = last_slice(p); unsigned int slice_avg, cpu, idle; long run_time = -1 * p->slice_time_ns; + long slice_time_ns = task_timeslice_ns(p); int w = MAX_BONUS, delta, bonus; /* - * Update time_slice. + * Update time_slice. Account for unused fragment, + * or excess time received due to missed tick. */ - p->slice_time_ns = task_timeslice_ns(p); - p->time_slice = task_timeslice(p); + p->slice_time_ns += slice_time_ns; + /* + * Not common, but this does happen on SMP systems. + * Timeslice theft of this magnitude has never been + * observed in the wild, so assume that this is BS, + * and give the poor task it's full slice. Theory: + * mostly idle task migrates between CPUs numerous + * times during it's slice, timestamp rounding leads + * to wildly inaccurate calculation. Rounding has + * maximum effect on those who stretch their slice, + * but is also fairly meaningless, so ignore it. + */ + if (unlikely(p->slice_time_ns < NS_TICK)) + p->slice_time_ns = slice_time_ns; + p->time_slice = NS_TO_JIFFIES(p->slice_time_ns); set_last_slice(p, p->time_slice); /* - 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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