linux-kernel - Re: [PATCH 3/4] nohz: Consolidate sleep time stats read code

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Date:	Sun, 18 Aug 2013 23:47:21 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Fernando Luis Vazquez Cao <fernando_b1@....ntt.co.jp>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Ven <arjan@...ux.intel.com>
Subject: Re: [PATCH 3/4] nohz: Consolidate sleep time stats read code

On Sun, Aug 18, 2013 at 07:00:01PM +0200, Oleg Nesterov wrote:
> On 08/16, Frederic Weisbecker wrote:
> >
> > get_cpu_idle_time_us() and get_cpu_iowait_time_us() mostly share
> > the same code. Lets consolidate both implementations.
> 
> Personally I like every patch which consolidates the code ;)
> 
> >  	do {
> >  		seq = read_seqcount_begin(&ts->sleeptime_seq);
> > -		if (ts->idle_active && !nr_iowait_cpu(cpu)) {
> > +		if (io)
> > +			sleep = ts->iowait_sleeptime;
> > +		else
> > +			sleep = ts->idle_sleeptime;
> > +
> > +		if (ts->idle_active)
> > +			continue;
> > +
> > +		if ((io && nr_iowait_cpu(cpu)) || (!io && !nr_iowait_cpu(cpu))) {
> >  			ktime_t delta = ktime_sub(now, ts->idle_entrytime);
> > -			idle = ktime_add(ts->idle_sleeptime, delta);
> > -		} else {
> > -			idle = ts->idle_sleeptime;
> > +			sleep = ktime_add(sleep, delta);
> >  		}
> >  	} while (read_seqcount_retry(&ts->sleeptime_seq, seq));
> 
> Cosmetic/subjective, feel free to ignore. but perhaps
> 
> 		if (ts->idle_active && io == !!nr_iowait_cpu(cpu)) {
> 			...
> 		}
> 
> looks more understandable.

Agreed, that's much better.

thanks!

> 
> Oleg.
> 
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