From: Yong Zhang <yong.zhang0@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Gregory Haskins <ghaskins@novell.com>
Subject: Re: [RFC][PATCH 01/10] sched: Change rt_task(prev) in pre_schedule_rt to likely
Date: Tue, 7 Dec 2010 11:25:43 +0800 [thread overview]
Message-ID: <AANLkTimO+aBQD530btPmH3o7j931KEmFP=GKia-039wO@mail.gmail.com> (raw)
In-Reply-To: <20101207021328.207196531@goodmis.org>
On Tue, Dec 7, 2010 at 9:58 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> From: Steven Rostedt <srostedt@redhat.com>
>
> As found with the branch annotation profiler, the unlikely(rt_task(prev))
> in pre_schedule_rt() is always wrong. In fact it should be likely due to
> the fact that we got to this function because we used prev's scheduling
> class (which had to be rt).
>
> Change the unlikely(rt_task(prev)) to likely(rt_task(prev))
I have sent a more radical patch before but it get ignored.
http://marc.info/?l=linux-kernel&m=126572702600950&w=2
>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Gregory Haskins <ghaskins@novell.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
> kernel/sched_rt.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
> index bea7d79..7a5c4db 100644
> --- a/kernel/sched_rt.c
> +++ b/kernel/sched_rt.c
> @@ -1474,7 +1474,7 @@ skip:
> static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
> {
> /* Try to pull RT tasks here if we lower this rq's prio */
> - if (unlikely(rt_task(prev)) && rq->rt.highest_prio.curr > prev->prio)
> + if (likely(rt_task(prev)) && rq->rt.highest_prio.curr > prev->prio)
IMHO, we can delete the checking for rt_task(prev).
Or am I missing something?
Thanks,
Yong
next prev parent reply other threads:[~2010-12-07 3:25 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-07 1:58 [RFC][PATCH 00/10] incorrect unlikely() and likely() cleanups Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 01/10] sched: Change rt_task(prev) in pre_schedule_rt to likely Steven Rostedt
2010-12-07 3:25 ` Yong Zhang [this message]
2010-12-07 3:32 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 02/10] mm: Remove likely() from mapping_unevictable() Steven Rostedt
2010-12-07 2:22 ` Steven Rostedt
2010-12-07 7:02 ` Nick Piggin
2010-12-07 13:06 ` Steven Rostedt
2010-12-07 16:26 ` Rik van Riel
2010-12-10 7:00 ` KOSAKI Motohiro
2010-12-10 7:06 ` Joe Perches
2010-12-10 8:08 ` Miles Bader
2010-12-11 0:09 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 03/10] workqueue: It is likely that WORKER_NOT_RUNNING is true Steven Rostedt
2010-12-07 9:49 ` Tejun Heo
2010-12-07 13:07 ` Steven Rostedt
2010-12-11 0:08 ` Steven Rostedt
2010-12-11 0:09 ` Tejun Heo
2010-12-11 0:12 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 04/10] sched: Change pick_next_task_rt from unlikely to likely Steven Rostedt
2010-12-07 2:46 ` Gregory Haskins
2010-12-07 2:59 ` Steven Rostedt
2010-12-11 0:07 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 05/10] mm: Remove likely() from grab_cache_page_write_begin() Steven Rostedt
2010-12-07 2:24 ` Steven Rostedt
2010-12-07 6:56 ` Nick Piggin
2010-12-07 1:58 ` [RFC][PATCH 06/10] sched: Remove unlikely() from rt_policy() in sched.c Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 07/10] x86: Remove unlikey()s from sched_switch segment tests Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 08/10] fs: Remove unlikely() from fput_light() Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 09/10] fs: Remove unlikely() from fget_light() Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 10/10] sched: Remove unlikely() from ttwu_post_activation Steven Rostedt
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