linux-kernel - Re: [RFC PATCH] sched: Kill WAKEUP

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Message-ID: <1311928322.3938.1589.camel@minggr.sh.intel.com>
Date:	Fri, 29 Jul 2011 16:32:02 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	Yong Zhang <yong.zhang0@...il.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"mingo@...e.hu" <mingo@...e.hu>,
	lkml <linux-kernel@...r.kernel.org>,
	Mike Galbraith <efault@....de>
Subject: Re: [RFC PATCH] sched: Kill WAKEUP_PREEMPT

On Fri, 2011-07-29 at 16:30 +0800, Lin Ming wrote:
> On Fri, 2011-07-29 at 16:20 +0800, Yong Zhang wrote:
> > On Fri, Jul 29, 2011 at 09:56:58AM +0200, Peter Zijlstra wrote:
> > > I've queued Lin's patch as I don't see the point of this thing either,
> > > normally WAKEUP_PREEMPT is enabled so it says || 0 which is kinda
> > > useless :-)
> > > 
> > > And I'm starting to think we should just kill all of WAKEUP_PREEMPT I
> > > don't think we ever want to disable it anyway.. 
> > 
> > Someting like this?
> > 
> > ---
> > From: Yong Zhang <yong.zhang0@...il.com>
> > Subject: [RFC PATCH] sched: Kill WAKEUP_PREEMPT
> > 
> > Per Peter Zijlstra:
> > > And I'm starting to think we should just kill all of WAKEUP_PREEMPT I
> > > don't think we ever want to disable it anyway..
> > 
> > Signed-off-by: Yong Zhang <yong.zhang0@...il.com>
> > ---
> >  kernel/sched_fair.c     |    8 +-------
> >  kernel/sched_features.h |    5 -----
> >  2 files changed, 1 insertions(+), 12 deletions(-)
> > 
> > diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> > index 46b7855..3c58042 100644
> > --- a/kernel/sched_fair.c
> > +++ b/kernel/sched_fair.c
> > @@ -1114,9 +1114,6 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> >  	 * narrow margin doesn't have to wait for a full slice.
> >  	 * This also mitigates buddy induced latencies under load.
> >  	 */
> > -	if (!sched_feat(WAKEUP_PREEMPT))
> > -		return;
> > -
> 
> -       /*
> -        * Ensure that a task that missed wakeup preemption by a
> -        * narrow margin doesn't have to wait for a full slice.
> -        * This also mitigates buddy induced latencies under load.
> -        */
> -       if (!sched_feat(WAKEUP_PREEMPT))
> -               return;
> -
> 
> Then remove the comments also.

Sorry, don't remove that comments.


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