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From: Rik van Riel <riel@surriel.com>
To: Josef Bacik <josef@toxicpanda.com>
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, pjt@google.com,
	dietmar.eggemann@arm.com, peterz@infradead.org, mingo@redhat.com,
	morten.rasmussen@arm.com, tglx@linutronix.de,
	mgorman@techsingularity.net, vincent.guittot@linaro.org
Subject: Re: [PATCH 09/10] sched,fair: add helper functions for flattened runqueue
Date: Mon, 01 Jul 2019 16:53:37 -0400	[thread overview]
Message-ID: <402b70ecb4d362ab6975b00a715872d585a18e35.camel@surriel.com> (raw)
In-Reply-To: <20190701202030.6sm7mdztyt6t5mui@macbook-pro-91.dhcp.thefacebook.com>

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On Mon, 2019-07-01 at 16:20 -0400, Josef Bacik wrote:
> 
> 
> > +static unsigned long task_se_h_weight(struct sched_entity *se)
> > +{
> > +	struct cfs_rq *cfs_rq;
> > +
> > +	if (!task_se_in_cgroup(se))
> > +		return se->load.weight;
> > +
> > +	cfs_rq = group_cfs_rq_of_parent(se);
> > +	update_cfs_rq_h_load(cfs_rq);
> > +
> > +	/* Reduce the load.weight by the h_load of the group the task
> > is in. */
> > +	return (cfs_rq->h_load * se->load.weight) >>
> > SCHED_FIXEDPOINT_SHIFT;
> 
> This should be
> 
> scale_load_down(cfs_rq->h_load * se->load.weight);

That may be the same mathematically, but it is
different conceptually.

If we convert CFS to have full load resolution with
cgroups (which we probably want), then scale_load_down
becomes a noop, while this shift continues doing the
right thing.

-- 
All Rights Reversed.

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  reply	other threads:[~2019-07-01 20:53 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-28 20:49 [PATCH RFC v2 0/10] sched,fair: flatten CPU controller runqueues Rik van Riel
2019-06-28 20:49 ` [PATCH 01/10] sched: introduce task_se_h_load helper Rik van Riel
2019-07-01 19:43   ` Josef Bacik
2019-06-28 20:49 ` [PATCH 02/10] sched: change /proc/sched_debug fields Rik van Riel
2019-07-01 19:52   ` Josef Bacik
2019-06-28 20:49 ` [PATCH 03/10] sched,fair: redefine runnable_load_avg as the sum of task_h_load Rik van Riel
2019-07-01 16:29   ` Josef Bacik
2019-07-01 16:47     ` Rik van Riel
2019-07-01 19:22       ` Josef Bacik
2019-07-01 19:32         ` Rik van Riel
2019-06-28 20:49 ` [PATCH 04/10] sched,fair: move runnable_load_avg to cfs_rq Rik van Riel
2019-06-28 20:49 ` [PATCH 05/10] sched,fair: remove cfs rqs from leaf_cfs_rq_list bottom up Rik van Riel
2019-07-04  9:33   ` Vincent Guittot
2019-07-05  1:02     ` Rik van Riel
2019-06-28 20:49 ` [PATCH 06/10] sched,cfs: use explicit cfs_rq of parent se helper Rik van Riel
2019-06-28 20:49 ` [PATCH 07/10] sched,cfs: fix zero length timeslice calculation Rik van Riel
2019-07-05 14:51   ` Vincent Guittot
2019-07-05 15:15     ` Rik van Riel
2019-06-28 20:49 ` [PATCH 08/10] sched,fair: refactor enqueue/dequeue_entity Rik van Riel
2019-06-28 20:49 ` [PATCH 09/10] sched,fair: add helper functions for flattened runqueue Rik van Riel
2019-07-01 20:20   ` Josef Bacik
2019-07-01 20:53     ` Rik van Riel [this message]
2019-06-28 20:49 ` [PATCH 10/10] sched,fair: flatten hierarchical runqueues Rik van Riel
2019-07-01 20:34   ` Josef Bacik
2019-07-01 20:58     ` Rik van Riel

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