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Message-ID: <1357787806.26078.4.camel@marge.simpson.net>
Date: Thu, 10 Jan 2013 04:16:46 +0100
From: Mike Galbraith <efault@....de>
To: Morten Rasmussen <Morten.Rasmussen@....com>
Cc: Alex Shi <alex.shi@...el.com>,
"mingo@...hat.com" <mingo@...hat.com>,
"peterz@...radead.org" <peterz@...radead.org>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"arjan@...ux.intel.com" <arjan@...ux.intel.com>,
"bp@...en8.de" <bp@...en8.de>, "pjt@...gle.com" <pjt@...gle.com>,
"namhyung@...nel.org" <namhyung@...nel.org>,
"vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"preeti@...ux.vnet.ibm.com" <preeti@...ux.vnet.ibm.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 04/22] sched: don't need go to smaller sched domain
On Wed, 2013-01-09 at 17:38 +0000, Morten Rasmussen wrote:
> On Sat, Jan 05, 2013 at 08:37:33AM +0000, Alex Shi wrote:
> > If parent sched domain has no task allowed cpu find. neither find in
> > it's child. So, go out to save useless checking.
> >
> > Signed-off-by: Alex Shi <alex.shi@...el.com>
> > ---
> > kernel/sched/fair.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 3c7b09a..ecfbf8e 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -3378,10 +3378,8 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
> > load_idx = sd->wake_idx;
> >
> > group = find_idlest_group(sd, p, cpu, load_idx);
>
> The previous patch changed the behavior of find_idlest_group() to
> returning the local group if it is suitable. This effectively means that
> you remove the recursive search for a suitable idle sched group. You
> could as well merge find_idlest_group() and find_idlest_cpu() to avoid
> iterating through the cpus of the same sched group twice.
find_idlest_* could stop when seeing 0 too, can't get much more idle.
-Mike
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