linux-kernel - Re: [patch v5 11/15] sched: add power/performance balance allow flag

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Message-ID: <1361368088.10155.36.camel@laptop>
Date:	Wed, 20 Feb 2013 14:48:08 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Alex Shi <alex.shi@...el.com>
Cc:	torvalds@...ux-foundation.org, mingo@...hat.com,
	tglx@...utronix.de, akpm@...ux-foundation.org,
	arjan@...ux.intel.com, bp@...en8.de, pjt@...gle.com,
	namhyung@...nel.org, efault@....de, vincent.guittot@...aro.org,
	gregkh@...uxfoundation.org, preeti@...ux.vnet.ibm.com,
	viresh.kumar@...aro.org, linux-kernel@...r.kernel.org,
	morten.rasmussen@....com
Subject: Re: [patch v5 11/15] sched: add power/performance balance allow flag

On Wed, 2013-02-20 at 14:37 +0100, Peter Zijlstra wrote:
> On Wed, 2013-02-20 at 20:04 +0800, Alex Shi wrote:
> 
> > >> @@ -5195,6 +5197,8 @@ static int load_balance(int this_cpu, struct rq
> > >> *this_rq,
> > >>                 .idle           = idle,
> > >>                 .loop_break     = sched_nr_migrate_break,
> > >>                 .cpus           = cpus,
> > >> +               .power_lb       = 0,
> > >> +               .perf_lb        = 1,
> > >>         };
> > >>  
> > >>         cpumask_copy(cpus, cpu_active_mask);
> > > 
> > > This construct allows for the possibility of power_lb=1,perf_lb=1, does
> > > that make sense? Why not have a single balance_policy enumeration?
> > 
> > (power_lb == 1 && perf_lb == 1) is incorrect and impossible to have.
> > 
> > (power_lb == 0 && perf_lb == 0) is possible and it means there is no any
> > balance on this cpu.
> > 
> > So, enumeration is not enough.
> 
> Huh.. both 0 doesn't make any sense either. If there's no balancing, we
> shouldn't be here to begin with.

Also, why is this in the lb_env at all, shouldn't we simply use the
global sched_balance_policy all over the place? Its not like we want to
change power/perf on a finer granularity.


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