linux-kernel - Re: [PATCH] sched: Call update_group_power only for local

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Message-Id: <1278611416.2834.12.camel@sbs-t61.sc.intel.com>
Date:	Thu, 08 Jul 2010 10:50:16 -0700
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Venkatesh Pallipadi <venki@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Gautham R Shenoy <ego@...ibm.com>,
	Joel Schopp <jschopp@...tin.ibm.com>,
	Michael Neuling <mikey@...ling.org>
Subject: Re: [PATCH] sched: Call update_group_power only for local_group

On Thu, 2010-07-08 at 10:49 -0700, Peter Zijlstra wrote:
> On Thu, 2010-07-08 at 10:45 -0700, Suresh Siddha wrote:
> >  
> > @@ -2456,6 +2454,9 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
> >  	init_sd_power_savings_stats(sd, sds, idle);
> >  	load_idx = get_sd_load_idx(sd, idle);
> >  
> > +	if (this_cpu == smp_processor_id())
> > +		update_group_power(sd, this_cpu);
> > +
> >  	do {
> >  		int local_group;
> 
> Which will break for nohz_idle_balance..

Then the logic is broken somewhere because update_group_power() reads
APERF/MPERF MSR's which doesn't make sense when this_cpu !=
smp_processor_id(). What am I missing?

thanks,
suresh

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