[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1332320819.18960.468.camel@twins>
Date: Wed, 21 Mar 2012 10:06:59 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: "Michael J. Wang" <mjwang@...adcom.com>
Cc: Yong Zhang <yong.zhang0@...il.com>,
"mingo@...e.hu" <mingo@...e.hu>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"rostedt@...dmis.org" <rostedt@...dmis.org>
Subject: RE: [PATCH 1/1] scheduler: minor improvement to
pick_next_highest_task_rt in linux-3.3
On Wed, 2012-03-21 at 07:49 +0000, Michael J. Wang wrote:
> > > Should I reformat my patch and send it again?
> >
> > It'll be better, and I think Peter/Ingo will happy with it.
> >
>
> OK. I will resend now. Thanks for all your help!
The resend didn't include the more details thing, so I fudged it by
hand. The queued thing now looks like this:
---
Subject: sched, rt: Minor improvement to pick_next_highest_task_rt
From: Michael J Wang <mjwang@...adcom.com>
Date: Mon, 19 Mar 2012 22:26:19 +0000
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.
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.
Signed-off-by: Michael J Wang <mjwang@...adcom.com>
Acked-by: Steven Rostedt <rostedt@...dmis.org>
Reviewed-by: Yong Zhang <yong.zhang0@...il.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/2EF88150C0EF2C43A218742ED384C1BC0FC83D6B@IRVEXCHMB08.corp.ad.broadcom.com
---
kernel/sched/rt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1428,7 +1428,7 @@ 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@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists