Date: Wed, 13 Apr 2016 09:40:38 +0100
From: Morten Rasmussen <morten.rasmussen@arm.com>
To: Yuyang Du <yuyang.du@intel.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>, peterz@infradead.org,
        mingo@kernel.org, linux-kernel@vger.kernel.org, bsegall@google.com,
        pjt@google.com, vincent.guittot@linaro.org, juri.lelli@arm.com
Subject: Re: [PATCH 2/4] sched/fair: Drop out incomplete current period when
 sched averages accrue
Message-ID: <20160413084037.GG18516@e105550-lin.cambridge.arm.com>
References: <1460327765-18024-1-git-send-email-yuyang.du@intel.com>
 <1460327765-18024-3-git-send-email-yuyang.du@intel.com>
 <570CE3F2.5000806@arm.com>
 <20160412201448.GL8697@intel.com>
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On Wed, Apr 13, 2016 at 04:14:48AM +0800, Yuyang Du wrote:
> On Tue, Apr 12, 2016 at 01:02:58PM +0100, Dietmar Eggemann wrote:
> > On 10/04/16 23:36, Yuyang Du wrote:
> > 
> > [...]
> > 
> > > @@ -2704,11 +2694,14 @@ static __always_inline int
> > >  __update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> > >  		  unsigned long weight, int running, struct cfs_rq *cfs_rq)
> > >  {
> > > -	u64 delta, scaled_delta, periods;
> > > -	u32 contrib;
> > > -	unsigned int delta_w, scaled_delta_w, decayed = 0;
> > > +	u64 delta;
> > > +	u32 contrib, periods;
> > >  	unsigned long scale_freq, scale_cpu;
> > >  
> > > +	/*
> > > +	 * now rolls down to a period boundary
> > > +	 */
> > > +	now = now && (u64)(~0xFFFFF);
> > 
> > This forces now to be 1.
> > 
> > s/&&/&
> 
> Duh, :)

Have you, or anybody else, actually tested the impact of this patch?