From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Joseph Salisbury <joseph.salisbury@canonical.com>,
Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Mike Galbraith <efault@gmx.de>,
omer.akram@canonical.com
Subject: Re: [v4.8-rc1 Regression] sched/fair: Apply more PELT fixes
Date: Wed, 19 Oct 2016 16:33:03 +0100 [thread overview]
Message-ID: <ee53f6b5-0fc9-537a-14ee-bfff87338369@arm.com> (raw)
In-Reply-To: <CAKfTPtBUfBz7q+w0JfT_3_18NteDF0BQfhRWsraJGY06U74hdw@mail.gmail.com>
On 19/10/16 12:25, Vincent Guittot wrote:
> On 19 October 2016 at 11:46, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>> On 18/10/16 12:56, Vincent Guittot wrote:
>>> Le Tuesday 18 Oct 2016 à 12:34:12 (+0200), Peter Zijlstra a écrit :
>>>> On Tue, Oct 18, 2016 at 11:45:48AM +0200, Vincent Guittot wrote:
>>>>> On 18 October 2016 at 11:07, Peter Zijlstra <peterz@infradead.org> wrote:
[...]
>> But this test only makes sure that we don't see any ghost contribution
>> (from non-existing cpus) any more.
>>
>> We should study the tg->se[i]->avg.load_avg for the hierarchy of tg's
>> (with the highest tg having a task enqueued) a little bit more, with and
>> without your v5 'sched: reflect sched_entity move into task_group's load'.
>
> Can you elaborate ?
I try :-)
I thought I will see some different behaviour because of the fact that
the tg se's are initialized differently [1024 versus 0].
But I can't spot any difference. The test case is running a sysbench
thread affine to cpu1 in tg_root/tg_1/tg_11/tg_111 on tip/sched/core on
an ARM64 Juno (6 logical cpus).
The moment the sysbench task is put into tg_111
tg_111->se[1]->avg.load_avg gets updated to 0 any way because of the
huge time difference between creating this tg and attaching a task to
it. So the tg->se[2]->avg.load_avg signals for tg_111, tg_11 and tg_1
look exactly the same w/o and w/ your patch.
But your patch helps in this (very synthetic) test case as well. W/o
your patch I see remaining tg->load_avg for tg_1 and tg_11 after the
test case has finished because the tg's were exclusively used on cpu1.
# cat /proc/sched_debug
cfs_rq[1]:/tg_1
.tg_load_avg_contrib : 0
.tg_load_avg : 5120 (5 (unused cpus) * 1024 * 1)
cfs_rq[1]:/tg_1/tg_11/tg_111
.tg_load_avg_contrib : 0
.tg_load_avg : 0
cfs_rq[1]:/tg_1/tg_11
.tg_load_avg_contrib : 0
.tg_load_avg : 5120
With your patch applied all the .tg_load_avg are 0.
next prev parent reply other threads:[~2016-10-19 15:33 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-07 19:38 [v4.8-rc1 Regression] sched/fair: Apply more PELT fixes Joseph Salisbury
2016-10-07 19:57 ` Linus Torvalds
2016-10-07 20:22 ` Joseph Salisbury
2016-10-07 20:37 ` Linus Torvalds
2016-10-08 8:00 ` Peter Zijlstra
2016-10-08 8:39 ` Ingo Molnar
2016-10-08 11:37 ` Vincent Guittot
2016-10-08 11:49 ` Mike Galbraith
2016-10-12 12:20 ` Vincent Guittot
2016-10-12 15:35 ` Joseph Salisbury
2016-10-12 16:21 ` Joseph Salisbury
2016-10-13 10:58 ` Vincent Guittot
2016-10-13 15:52 ` Joseph Salisbury
2016-10-13 16:48 ` Vincent Guittot
2016-10-13 18:49 ` Dietmar Eggemann
2016-10-13 21:34 ` Vincent Guittot
2016-10-14 8:24 ` Vincent Guittot
2016-10-14 13:10 ` Dietmar Eggemann
2016-10-14 15:18 ` Vincent Guittot
2016-10-14 16:04 ` Joseph Salisbury
2016-10-17 9:09 ` Vincent Guittot
2016-10-17 11:49 ` Dietmar Eggemann
2016-10-17 13:19 ` Peter Zijlstra
2016-10-17 13:54 ` Vincent Guittot
2016-10-17 22:52 ` Dietmar Eggemann
2016-10-18 8:43 ` Vincent Guittot
2016-10-18 9:07 ` Peter Zijlstra
2016-10-18 9:45 ` Vincent Guittot
2016-10-18 10:34 ` Peter Zijlstra
2016-10-18 11:56 ` Vincent Guittot
2016-10-18 21:58 ` Joonwoo Park
2016-10-19 6:42 ` Vincent Guittot
2016-10-19 9:46 ` Dietmar Eggemann
2016-10-19 11:25 ` Vincent Guittot
2016-10-19 15:33 ` Dietmar Eggemann [this message]
2016-10-19 17:33 ` Joonwoo Park
2016-10-19 17:50 ` Vincent Guittot
2016-10-19 11:33 ` Peter Zijlstra
2016-10-19 11:50 ` Vincent Guittot
2016-10-19 13:30 ` Morten Rasmussen
2016-10-19 17:41 ` Vincent Guittot
2016-10-20 7:56 ` Morten Rasmussen
2016-10-19 14:49 ` Joseph Salisbury
2016-10-19 14:53 ` Vincent Guittot
2016-10-18 11:15 ` Dietmar Eggemann
2016-10-18 12:07 ` Peter Zijlstra
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