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Date: Tue, 17 Dec 2013 16:38:09 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Alex Shi <alex.shi@linaro.org>, "mingo@redhat.com" <mingo@redhat.com>,
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Subject: Re: [PATCH 4/4] sched: bias to target cpu load to reduce task moving
Message-ID: <20131217153809.GP21999@twins.programming.kicks-ass.net>
References: <1386061556-28233-1-git-send-email-alex.shi@linaro.org>
 <1386061556-28233-5-git-send-email-alex.shi@linaro.org>
 <20131217141012.GG10134@e103034-lin>
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On Tue, Dec 17, 2013 at 02:10:12PM +0000, Morten Rasmussen wrote:
> > @@ -4135,7 +4141,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
> >  			if (local_group)
> >  				load = source_load(i);
> >  			else
> > -				load = target_load(i);
> > +				load = target_load(i, sd->imbalance_pct);
> 
> Don't you apply imbalance_pct twice here? Later on in
> find_idlest_group() you have:
> 
> 	if (!idlest || 100*this_load < imbalance*min_load)
> 		return NULL;
> 
> where min_load comes from target_load().

Yes! exactly! this doesn't make any sense.