From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Rik van Riel <riel@surriel.com>, peterz@infradead.org
Cc: mingo@redhat.com, linux-kernel@vger.kernel.org,
kernel-team@fb.com, morten.rasmussen@arm.com, tglx@linutronix.de,
dietmar.eggeman@arm.com, mgorman@techsingularity.com,
vincent.guittot@linaro.org
Subject: Re: [PATCH 5/8] sched,cfs: use explicit cfs_rq of parent se helper
Date: Mon, 24 Jun 2019 13:24:10 +0200 [thread overview]
Message-ID: <1f90005d-1130-399b-8642-9e1ad7089ab3@arm.com> (raw)
In-Reply-To: <c5c73fd374ed952eedc46a89af294e1d521609b2.camel@surriel.com>
On 6/20/19 6:29 PM, Rik van Riel wrote:
> On Thu, 2019-06-20 at 18:23 +0200, Dietmar Eggemann wrote:
>> On 6/12/19 9:32 PM, Rik van Riel wrote:
[...]
>>> @@ -7779,7 +7788,7 @@ static void update_cfs_rq_h_load(struct
>>> cfs_rq *cfs_rq)
>>>
>>> WRITE_ONCE(cfs_rq->h_load_next, NULL);
>>> for_each_sched_entity(se) {
>>> - cfs_rq = cfs_rq_of(se);
>>> + cfs_rq = group_cfs_rq_of_parent(se);
>>
>> Why do you change this here? task_se_h_load() calls
>> update_cfs_rq_h_load() with cfs_rq = group_cfs_rq_of_parent(se)
>> because
>> the task might not be on the cfs_rq yet.
>
> Because patch 6 points cfs_rq_of(se) at the CPU's top level
> cfs_rq for every task se ...
>
> ... but I guess since I have not changed where the cfs_rq_of
> points for cgroup sched_entities, this change is not necessary
> at this time, and I should be able to go without it, in this
> function.
IMHO, since you only change set_task_rq() (p->se.cfs_rq =
&cpu_rq(cpu)->cfs instead of tg->cfs_rq[cpu] in 8/8) (used for a task)
and not init_tg_cfs_entry() (used for a taskgroup), 'cfs_rq_of(se) ==
se->parent->my_q' should still be true in update_cfs_rq_h_load().
update_cfs_rq_h_load() only deals with se's representing taskgroups. So
cfs_rq_of(se) and group_cfs_rq_of_parent(se) should deliver the same
result for these se's.
>> But inside update_cfs_rq_h_load() the first se is derived from
>> cfs_rq->tg->se[cpu_of(rq)] so in the first for_each_sched_entity()
>> loop
>> we should still start with group_cfs_rq() (se->my_q) ?
Here I was wrong. The first loop did use cfs_rq_of() and not group_cfs_rq().
[...]
next prev parent reply other threads:[~2019-06-24 11:24 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 19:32 [RFC] sched,cfs: flatten CPU controller runqueues Rik van Riel
2019-06-12 19:32 ` [PATCH 1/8] sched: introduce task_se_h_load helper Rik van Riel
2019-06-19 12:52 ` Dietmar Eggemann
2019-06-19 13:57 ` Rik van Riel
2019-06-19 15:18 ` Dietmar Eggemann
2019-06-19 15:55 ` Rik van Riel
2019-06-12 19:32 ` [PATCH 2/8] sched: change /proc/sched_debug fields Rik van Riel
2019-06-12 19:32 ` [PATCH 3/8] sched,fair: redefine runnable_load_avg as the sum of task_h_load Rik van Riel
2019-06-18 9:08 ` Dietmar Eggemann
2019-06-26 14:34 ` Dietmar Eggemann
2019-06-12 19:32 ` [PATCH 4/8] sched,fair: remove cfs rqs from leaf_cfs_rq_list bottom up Rik van Riel
2019-06-12 19:32 ` [PATCH 5/8] sched,cfs: use explicit cfs_rq of parent se helper Rik van Riel
2019-06-20 16:23 ` Dietmar Eggemann
2019-06-20 16:29 ` Rik van Riel
2019-06-24 11:24 ` Dietmar Eggemann [this message]
2019-06-26 15:58 ` Dietmar Eggemann
2019-06-26 16:15 ` Rik van Riel
2019-06-12 19:32 ` [PATCH 6/8] sched,cfs: fix zero length timeslice calculation Rik van Riel
2019-06-12 19:32 ` [PATCH 7/8] sched,fair: refactor enqueue/dequeue_entity Rik van Riel
2019-06-12 19:32 ` [PATCH 8/8] sched,fair: flatten hierarchical runqueues Rik van Riel
2019-06-25 9:50 ` Dietmar Eggemann
2019-06-25 13:51 ` Rik van Riel
2019-06-28 10:26 ` Dietmar Eggemann
2019-06-28 19:36 ` Rik van Riel
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