linux-kernel - Re: [PATCH 0/6] sched/fair: Compute capacity invariant load/utilization tracking

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Message-ID: <20150907132159.GU18673@twins.programming.kicks-ass.net>
Date:	Mon, 7 Sep 2015 15:21:59 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Morten Rasmussen <morten.rasmussen@....com>
Cc:	mingo@...hat.com, vincent.guittot@...aro.org,
	daniel.lezcano@...aro.org,
	Dietmar Eggemann <Dietmar.Eggemann@....com>,
	yuyang.du@...el.com, mturquette@...libre.com, rjw@...ysocki.net,
	Juri Lelli <Juri.Lelli@....com>, sgurrappadi@...dia.com,
	pang.xunlei@....com.cn, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/6] sched/fair: Compute capacity invariant
 load/utilization tracking

On Mon, Sep 07, 2015 at 02:42:20PM +0200, Peter Zijlstra wrote:
> I'm of a mind to apply these patches; with two patches on top, which
> I'll post shortly.

---
Subject: sched: Rename scale()
From: Peter Zijlstra <peterz@...radead.org>
Date: Mon Sep 7 15:05:42 CEST 2015

Rename scale() to cap_scale() to better reflect its purpose, it is
after all not a general purpose scale function, it has
SCHED_CAPACITY_SHIFT hardcoded in it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/fair.c |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2515,7 +2515,7 @@ static u32 __compute_runnable_contrib(u6
 	return contrib + runnable_avg_yN_sum[n];
 }
 
-#define scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT)
+#define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT)
 
 /*
  * We can represent the historical contribution to runnable average as the
@@ -2588,7 +2588,7 @@ __update_load_avg(u64 now, int cpu, stru
 		 * period and accrue it.
 		 */
 		delta_w = 1024 - delta_w;
-		scaled_delta_w = scale(delta_w, scale_freq);
+		scaled_delta_w = cap_scale(delta_w, scale_freq);
 		if (weight) {
 			sa->load_sum += weight * scaled_delta_w;
 			if (cfs_rq) {
@@ -2597,7 +2597,7 @@ __update_load_avg(u64 now, int cpu, stru
 			}
 		}
 		if (running)
-			sa->util_sum += scale(scaled_delta_w, scale_cpu);
+			sa->util_sum += cap_scale(scaled_delta_w, scale_cpu);
 
 		delta -= delta_w;
 
@@ -2614,25 +2614,25 @@ __update_load_avg(u64 now, int cpu, stru
 
 		/* Efficiently calculate \sum (1..n_period) 1024*y^i */
 		contrib = __compute_runnable_contrib(periods);
-		contrib = scale(contrib, scale_freq);
+		contrib = cap_scale(contrib, scale_freq);
 		if (weight) {
 			sa->load_sum += weight * contrib;
 			if (cfs_rq)
 				cfs_rq->runnable_load_sum += weight * contrib;
 		}
 		if (running)
-			sa->util_sum += scale(contrib, scale_cpu);
+			sa->util_sum += cap_scale(contrib, scale_cpu);
 	}
 
 	/* Remainder of delta accrued against u_0` */
-	scaled_delta = scale(delta, scale_freq);
+	scaled_delta = cap_scale(delta, scale_freq);
 	if (weight) {
 		sa->load_sum += weight * scaled_delta;
 		if (cfs_rq)
 			cfs_rq->runnable_load_sum += weight * scaled_delta;
 	}
 	if (running)
-		sa->util_sum += scale(scaled_delta, scale_cpu);
+		sa->util_sum += cap_scale(scaled_delta, scale_cpu);
 
 	sa->period_contrib += delta;
 
--
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