From: Peter Zijlstra <peterz@infradead.org>
To: Rik van Riel <riel@surriel.com>
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, pjt@google.com,
dietmar.eggemann@arm.com, mingo@redhat.com,
morten.rasmussen@arm.com, tglx@linutronix.de,
mgorman@techsingularity.net, vincent.guittot@linaro.org
Subject: Re: [PATCH 09/14] sched,fair: refactor enqueue/dequeue_entity
Date: Wed, 31 Jul 2019 17:30:27 +0200 [thread overview]
Message-ID: <20190731153027.GV31381@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <461f14cafabb7e6f78556f138b6aa619eff12dee.camel@surriel.com>
On Wed, Jul 31, 2019 at 11:03:01AM -0400, Rik van Riel wrote:
> I think I understand the problem you are pointing out, but if
> update_load_avg() keeps the load average for the runqueue unchanged
> (because that is rate limited to once a jiffy, and has been like that
> for a while), why would calc_group_shares() result in a different
> value than what it returned the last time?
>
> What am I overlooking?
I'm thinking you're thinking (3):
tg->weight * grq->avg.load_avg
shares = ------------------------------
tg->load_avg
Where: tg->load_avg ~= \Sum grq->avg.load_avg
Which is the straight forward shares calculation, and purely depends on
the load averages (which haven't been changed etc..)
But what we actually do is (6):
tg->weight * grq->avg.load_avg
shares = ---------------------------------------------------------------------------
tg->load_avg - grq->avg.load_avg + max(grq->load.weight, grq->avg.load_avg)
And even if tg->load_avg and grq->avg.load_avg haven't changed,
grq->load.weight most certainly has.
next prev parent reply other threads:[~2019-07-31 15:30 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 17:33 [PATCH RFC v3 0/14] sched,fair: flatten CPU controller runqueues Rik van Riel
2019-07-22 17:33 ` [PATCH 01/14] sched: introduce task_se_h_load helper Rik van Riel
2019-08-12 17:40 ` Dietmar Eggemann
2019-07-22 17:33 ` [PATCH 02/14] sched: change /proc/sched_debug fields Rik van Riel
2019-07-22 17:33 ` [PATCH 03/14] sched,fair: redefine runnable_load_avg as the sum of task_h_load Rik van Riel
2019-07-29 20:05 ` Peter Zijlstra
2019-07-29 21:13 ` Rik van Riel
2019-07-29 20:11 ` Peter Zijlstra
2019-07-29 20:26 ` Peter Zijlstra
2019-07-22 17:33 ` [PATCH 04/14] sched,fair: move runnable_load_avg to cfs_rq Rik van Riel
2019-07-30 8:55 ` Peter Zijlstra
2019-07-22 17:33 ` [PATCH 06/14] sched,cfs: use explicit cfs_rq of parent se helper Rik van Riel
2019-07-22 17:33 ` [PATCH 07/14] sched,cfs: fix zero length timeslice calculation Rik van Riel
2019-07-22 17:33 ` [PATCH 08/14] sched,fair: simplify timeslice length code Rik van Riel
2019-07-22 17:33 ` [PATCH 09/14] sched,fair: refactor enqueue/dequeue_entity Rik van Riel
2019-07-30 9:36 ` Peter Zijlstra
2019-07-30 12:58 ` Rik van Riel
2019-07-31 9:35 ` Peter Zijlstra
2019-07-31 15:03 ` Rik van Riel
2019-07-31 15:30 ` Peter Zijlstra [this message]
2019-07-22 17:33 ` [PATCH 10/14] sched,fair: add helper functions for flattened runqueue Rik van Riel
2019-07-22 17:33 ` [PATCH 11/14] sched,fair: flatten hierarchical runqueues Rik van Riel
2019-07-22 17:33 ` [PATCH 12/14] sched,fair: track cfs_rq->max_h_load for more legitimate h_weight Rik van Riel
2019-07-22 17:33 ` [PATCH 13/14] sched,fair: flatten update_curr functionality Rik van Riel
2019-07-22 17:33 ` [PATCH 14/14] sched,fair: propagate sum_exec_runtime up the hierarchy Rik van Riel
2019-07-30 16:29 ` [PATCH RFC v3 0/14] sched,fair: flatten CPU controller runqueues Peter Zijlstra
2019-07-30 18:27 ` Rik van Riel
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