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Date:   Sat, 13 May 2023 11:32:34 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc:     Ingo Molnar <mingo@kernel.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Qais Yousef <qyousef@layalina.io>,
        Kajetan Puchalski <kajetan.puchalski@arm.com>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Vincent Donnefort <vdonnefort@google.com>,
        Quentin Perret <qperret@google.com>,
        Abhijeet Dharmapurikar <adharmap@quicinc.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] sched/fair, cpufreq: Introduce 'runnable boosting'
Message-ID: <20230513093234.GB4253@hirez.programming.kicks-ass.net>
References: <20230512101029.342823-1-dietmar.eggemann@arm.com>
 <20230512101029.342823-3-dietmar.eggemann@arm.com>
 <20230512112229.GW4253@hirez.programming.kicks-ass.net>
 <251b524a-2c44-3892-1bae-03f879d6a64b@arm.com>
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In-Reply-To: <251b524a-2c44-3892-1bae-03f879d6a64b@arm.com>
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On Fri, May 12, 2023 at 04:39:51PM +0200, Dietmar Eggemann wrote:
> On 12/05/2023 13:22, Peter Zijlstra wrote:
> > On Fri, May 12, 2023 at 12:10:29PM +0200, Dietmar Eggemann wrote:
> > 
> >> -static unsigned long cpu_util(int cpu, struct task_struct *p, int dst_cpu)
> >> +static unsigned long
> >> +cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
> >>  {
> >>  	struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
> >>  	unsigned long util = READ_ONCE(cfs_rq->avg.util_avg);
> >> +	unsigned long runnable;
> >> +
> >> +	runnable = boost ? READ_ONCE(cfs_rq->avg.runnable_avg) : 0;
> >> +	util = max(util, runnable);
> >>  
> > 	if (boost)
> > 		util = max(util, READ_ONCE(cfs_rq->avg.runnable_avg));
> 
> I need the util_est = max(util_est, runnable) further down as well. Just
> want to fetch runnable only once.

Ah, fair enought; but still, please use a regular if().