From: Mel Gorman <mgorman@suse.de>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Phil Auld <pauld@redhat.com>, Parth Shah <parth@linux.ibm.com>,
Hillf Danton <hdanton@sina.com>
Subject: Re: [PATCH v3 4/5] sched/pelt: Add a new runnable average signal
Date: Fri, 21 Feb 2020 09:04:48 +0000 [thread overview]
Message-ID: <20200221090448.GQ3420@suse.de> (raw)
In-Reply-To: <d9f78b94-2455-e000-82bd-c00cfb9bbc8e@arm.com>
On Thu, Feb 20, 2020 at 04:11:18PM +0000, Valentin Schneider wrote:
> On 20/02/2020 14:36, Vincent Guittot wrote:
> > I agree that setting by default to SCHED_CAPACITY_SCALE is too much
> > for little core.
> > The problem for little core can be fixed by using the cpu capacity instead
> >
>
> So that's indeed better for big.LITTLE & co. Any reason however for not
> aligning with the initialization of util_avg ?
>
> With the default MC imbalance_pct (117), it takes 875 utilization to make
> a single CPU group (with 1024 capacity) overloaded (group_is_overloaded()).
> For a completely idle CPU, that means forking at least 3 tasks (512 + 256 +
> 128 util_avg)
>
> With your change, it only takes 2 tasks. I know I'm being nitpicky here, but
> I feel like those should be aligned, unless we have a proper argument against
> it - in which case this should also appear in the changelog with so far only
> mentions issues with util_avg migration, not the fork time initialization.
>
So, what is the way forward here? Should this patch be modified now,
a patch be placed on top or go with what we have for the moment that
works for symmetric CPUs and deal with the asym case later?
I do not have any asym systems at all so I've no means of checking
whether there is a problem or not.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2020-02-21 9:04 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 15:27 [PATCH v2 0/5] remove runnable_load_avg and improve group_classify Vincent Guittot
2020-02-14 15:27 ` [PATCH v2 1/5] sched/fair: Reorder enqueue/dequeue_task_fair path Vincent Guittot
2020-02-18 12:37 ` Dietmar Eggemann
2020-02-18 13:22 ` Peter Zijlstra
2020-02-18 14:15 ` Vincent Guittot
2020-02-19 11:07 ` Dietmar Eggemann
2020-02-19 16:26 ` Vincent Guittot
2020-02-20 13:38 ` Dietmar Eggemann
[not found] ` <20200222152541.GA11669@geo.homenetwork>
2020-02-26 16:30 ` Vincent Guittot
2020-02-14 15:27 ` [PATCH v2 2/5] sched/numa: Replace runnable_load_avg by load_avg Vincent Guittot
2020-02-18 12:37 ` Dietmar Eggemann
2020-02-18 13:50 ` Mel Gorman
2020-02-18 14:17 ` Vincent Guittot
2020-02-18 14:42 ` Dietmar Eggemann
2020-02-18 14:54 ` Valentin Schneider
2020-02-18 15:33 ` Vincent Guittot
2020-02-18 15:38 ` Mel Gorman
2020-02-18 16:50 ` Valentin Schneider
2020-02-18 17:41 ` Mel Gorman
2020-02-18 17:54 ` Valentin Schneider
2020-02-18 16:51 ` Vincent Guittot
2020-02-14 15:27 ` [PATCH v2 3/5] sched/pelt: Remove unused runnable load average Vincent Guittot
2020-02-21 9:57 ` Dietmar Eggemann
2020-02-21 11:56 ` Vincent Guittot
2020-02-14 15:27 ` [PATCH v2 4/5] sched/pelt: Add a new runnable average signal Vincent Guittot
2020-02-18 14:54 ` Valentin Schneider
2020-02-18 15:12 ` Peter Zijlstra
2020-02-18 15:28 ` Vincent Guittot
2020-02-18 16:30 ` Valentin Schneider
2020-02-18 21:19 ` Valentin Schneider
2020-02-19 9:02 ` Vincent Guittot
2020-02-19 9:08 ` Mel Gorman
2020-02-19 12:55 ` [PATCH v3 " Vincent Guittot
2020-02-19 14:02 ` Mel Gorman
2020-02-19 20:10 ` Valentin Schneider
2020-02-20 14:36 ` Vincent Guittot
2020-02-20 16:11 ` Valentin Schneider
2020-02-21 8:56 ` Vincent Guittot
2020-02-24 15:57 ` Valentin Schneider
2020-02-21 9:04 ` Mel Gorman [this message]
2020-02-21 9:25 ` Vincent Guittot
2020-02-21 10:40 ` Mel Gorman
2020-02-21 13:28 ` Vincent Guittot
2020-02-20 15:04 ` Dietmar Eggemann
2020-02-21 9:44 ` Dietmar Eggemann
2020-02-21 11:47 ` Vincent Guittot
2020-02-14 15:27 ` [PATCH v2 5/5] sched/fair: Take into account runnable_avg to classify group Vincent Guittot
2020-02-15 21:58 ` [PATCH v2 0/5] remove runnable_load_avg and improve group_classify Mel Gorman
2020-02-21 9:58 ` Dietmar Eggemann
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