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

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Date:	Wed, 20 Feb 2013 16:22:34 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Alex Shi <alex.shi@...el.com>
Cc:	torvalds@...ux-foundation.org, mingo@...hat.com,
	peterz@...radead.org, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, 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, Feb 20, 2013 at 10:20:19PM +0800, Alex Shi wrote:
> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >> index 2e8131d..0047856 100644
> >> --- a/kernel/sched/fair.c
> >> +++ b/kernel/sched/fair.c
> >> @@ -4053,6 +4053,8 @@ struct lb_env {
> >>  	unsigned int		loop;
> >>  	unsigned int		loop_break;
> >>  	unsigned int		loop_max;
> >> +	int			power_lb;  /* if power balance needed */
> >> +	int			perf_lb;   /* if performance balance needed */
> > 
> > Those look like they're used like simple boolean flags. Why not make
> > them such, i.e. bitfields? See struct perf_event_attr for an example.
> 
> there are 11 long words in struct lb_env now. use boolean or bitfields
> can't save much space.

Now now maybe.

Btw, there's a ->flags variable there which simply cries to get another
LBF_* flag or two. This way you don't add any new members at all and
don't enlarge the struct.

> and not use conveniently.

Make yourself accessor functions or whatever.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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