Messages in this thread Patch in this message | | | Date | Wed, 21 Mar 2012 09:40:50 +0800 | From | Yong Zhang <> | Subject | Re: [PATCH 1/1] scheduler: minor improvement to pick_next_highest_task_rt in linux-3.3 |
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On Mon, Mar 19, 2012 at 10:26:19PM +0000, Michael J. Wang wrote: > From: Michael J Wang <mjwang@broadcom.com> > > Avoid extra work by continuing on to the next rt_rq if the highest prio task in current rt_rq is the same priority as our candidate task. > > Signed-off-by: Michael J Wang <mjwang@broadcom.com> > > --- > > More detailed explanation: if next is not NULL, then we have found a candidate task, and its priority is next->prio. Now we are looking for an even higher priority task in the other rt_rq's. idx is the highest priority in the current candidate rt_rq. In the current 3.3 code, if idx is equal to next->prio, we would start scanning the tasks in that rt_rq and replace the current candidate task with a task from that rt_rq. But the new task would only have a priority that is equal to our previous candidate task, so we have not advanced our goal of finding a higher prio task. So we should avoid the extra work by continuing on to the next rt_rq if idx is equal to next->prio. >
You should limit characters of each line to 80 if possible.
And before sending you patch, linux-source/scripts/checkpatch.pl maybe give you some clues whether there is some warning/error. If there are, fix them.
Only for what your patch wants to show: Reviewed-by: Yong Zhang <yong.zhang0@gmail.com>
Thanks, Yong
> --- linux-3.3/kernel/sched/rt.c.orig 2012-03-18 16:15:34.000000000 -0700 > +++ linux-3.3/kernel/sched/rt.c 2012-03-19 14:52:54.585391702 -0700 > @@ -1403,7 +1403,7 @@ static struct task_struct *pick_next_hig > next_idx: > if (idx >= MAX_RT_PRIO) > continue; > - if (next && next->prio < idx) > + if (next && next->prio <= idx) > continue; > list_for_each_entry(rt_se, array->queue + idx, run_list) { > struct task_struct *p; > > > > > > > -- > 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/
-- Only stand for myself
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