From: Peter Zijlstra <peterz@infradead.org>
To: Rik van Riel <riel@surriel.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Frederic Weisbecker <fweisbec@gmail.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Quentin Perret <quentin.perret@arm.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Patrick Bellasi <patrick.bellasi@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/7] sched/fair: Rename weighted_cpuload() to cpu_load()
Date: Mon, 27 May 2019 21:13:20 +0200 [thread overview]
Message-ID: <20190527191320.GH2623@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <686351aab73911569a7c22a7e104d1b9f0d579b9.camel@surriel.com>
On Mon, May 27, 2019 at 12:24:07PM -0400, Rik van Riel wrote:
> On Mon, 2019-05-27 at 07:21 +0100, Dietmar Eggemann wrote:
> > This is done to align the per cpu (i.e. per rq) load with the util
> > counterpart (cpu_util(int cpu)). The term 'weighted' is not needed
> > since there is no 'unweighted' load to distinguish it from.
>
> I can see why you want to make cpu_util() and cpu_load()
> have the same parameter, but ...
>
> > @@ -7931,7 +7928,7 @@ static inline void update_sg_lb_stats(struct
> > lb_env *env,
> > if ((env->flags & LBF_NOHZ_STATS) &&
> > update_nohz_stats(rq, false))
> > env->flags |= LBF_NOHZ_AGAIN;
> >
> > - sgs->group_load += weighted_cpuload(rq);
> > + sgs->group_load += cpu_load(i);
> > sgs->group_util += cpu_util(i);
> > sgs->sum_nr_running += rq->cfs.h_nr_running;
>
> ... now we end up dereferencing cpu_rq(cpu) 3 times.
>
> I guess per-cpu variables are so cheap that we should
> never notice, but I thought I'd ask anyway while looking
> over these patches :)
I was going to say CSE should fix that, but then I noticed per_cpu
contains that hideous RELOC_HIDE() thing and I figure that might
confuse GCC enough to break that :/
next prev parent reply other threads:[~2019-05-27 19:13 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-27 6:21 [PATCH 0/7] sched: Remove per rq load array Dietmar Eggemann
2019-05-27 6:21 ` [PATCH 1/7] sched: Remove rq->cpu_load[] update code Dietmar Eggemann
2019-05-27 16:09 ` Rik van Riel
2019-06-03 13:02 ` [tip:sched/core] sched/fair: Remove the " tip-bot for Dietmar Eggemann
2019-05-27 6:21 ` [PATCH 2/7] sched/fair: Replace source_load() & target_load() w/ weighted_cpuload() Dietmar Eggemann
2019-05-27 16:09 ` Rik van Riel
2019-05-28 10:24 ` Dietmar Eggemann
2019-05-28 10:53 ` Peter Zijlstra
2019-06-03 13:02 ` [tip:sched/core] sched/fair: Replace source_load() & target_load() with weighted_cpuload() tip-bot for Dietmar Eggemann
2019-05-27 6:21 ` [PATCH 3/7] sched/debug: Remove sd->*_idx range on sysctl Dietmar Eggemann
2019-05-27 16:10 ` Rik van Riel
2019-06-03 13:03 ` [tip:sched/core] " tip-bot for Dietmar Eggemann
2019-05-27 6:21 ` [PATCH 4/7] sched: Remove rq->cpu_load[] Dietmar Eggemann
2019-05-27 16:10 ` Rik van Riel
2019-06-03 13:04 ` [tip:sched/core] sched/core: " tip-bot for Dietmar Eggemann
2019-05-27 6:21 ` [PATCH 5/7] sched: Remove sd->*_idx Dietmar Eggemann
2019-05-27 16:12 ` Rik van Riel
2019-06-03 13:04 ` [tip:sched/core] sched/core: " tip-bot for Dietmar Eggemann
2019-05-27 6:21 ` [PATCH 6/7] sched/fair: Remove sgs->sum_weighted_load Dietmar Eggemann
2019-05-27 14:07 ` Vincent Guittot
2019-05-27 16:13 ` Rik van Riel
2019-06-03 13:05 ` [tip:sched/core] " tip-bot for Dietmar Eggemann
2019-05-27 6:21 ` [PATCH 7/7] sched/fair: Rename weighted_cpuload() to cpu_load() Dietmar Eggemann
2019-05-27 13:31 ` Vincent Guittot
2019-05-27 16:24 ` Rik van Riel
2019-05-27 19:13 ` Peter Zijlstra [this message]
2019-06-18 12:23 ` Dietmar Eggemann
2019-06-25 8:29 ` [tip:sched/core] sched/fair: Rename weighted_cpuload() to cpu_runnable_load() tip-bot for Dietmar Eggemann
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