From: Yuyang Du <yuyang.du@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Mike Galbraith <umgwanakikbuti@gmail.com>,
Benjamin Segall <bsegall@google.com>,
Paul Turner <pjt@google.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Matt Fleming <matt@codeblueprint.co.uk>
Subject: Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks
Date: Wed, 10 Aug 2016 07:19:55 +0800 [thread overview]
Message-ID: <20160809231955.GA3273@intel.com> (raw)
In-Reply-To: <20160624130324.GZ30909@twins.programming.kicks-ass.net>
On Fri, Jun 24, 2016 at 03:03:24PM +0200, Peter Zijlstra wrote:
> > Task's last_update_time means this task is detached from fair queue. This
> > (re)definition is by all means much better than migrating. No?
>
> I would maybe redefine it as an up-to-date marker for a migration across
> a clock discontinuity. Both CPU migration and group movement suffer from
> this, albeit for different reasons.
>
> In the CPU migration case we simply cannot tell time by our refusal to
> acquire the old rq lock. So we age to the last time we 'know' and then
> mark it up-to-date.
>
> For the cgroup move the timelines simply _are_ discontinuous. So we have
> to mark it up-to-date after we update it to the instant of detach, such
> that when we attach it to the new group we don't try to age it across
> the time difference.
Got it. I'm glad to see you worked out all these.
It's like I am replying to an email in the last century, sorry, but I was
distracted for many other things.
next prev parent reply other threads:[~2016-08-10 18:45 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-17 12:01 [PATCH 0/4] sched/fair: Fix PELT wobblies Peter Zijlstra
2016-06-17 12:01 ` [PATCH 1/4] sched: Optimize fork() paths Peter Zijlstra
2016-06-17 12:01 ` [PATCH 2/4] sched/fair: Fix PELT integrity for new groups Peter Zijlstra
2016-06-17 13:51 ` Vincent Guittot
2016-06-17 12:01 ` [PATCH 3/4] sched,cgroup: Fix cpu_cgroup_fork() Peter Zijlstra
2016-06-17 13:58 ` Vincent Guittot
2016-06-17 14:06 ` Peter Zijlstra
2016-06-17 12:01 ` [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks Peter Zijlstra
2016-06-17 14:09 ` Vincent Guittot
2016-06-17 14:28 ` Peter Zijlstra
2016-06-17 16:02 ` Peter Zijlstra
2016-06-17 16:14 ` Vincent Guittot
2016-06-17 16:18 ` Peter Zijlstra
2016-06-19 22:55 ` Yuyang Du
2016-06-20 9:23 ` Vincent Guittot
2016-06-20 9:52 ` Peter Zijlstra
2016-06-20 10:07 ` Vincent Guittot
2016-06-21 11:43 ` Peter Zijlstra
2016-06-21 12:36 ` Vincent Guittot
2016-06-21 12:47 ` Peter Zijlstra
2016-06-21 12:56 ` Vincent Guittot
2016-06-20 11:35 ` Dietmar Eggemann
2016-06-20 12:35 ` Vincent Guittot
2016-06-20 14:49 ` Dietmar Eggemann
2016-06-21 8:41 ` Peter Zijlstra
2016-06-21 4:51 ` Yuyang Du
2016-06-24 13:03 ` Peter Zijlstra
2016-08-09 23:19 ` Yuyang Du [this message]
2016-06-21 13:17 ` Peter Zijlstra
2016-06-21 13:29 ` Vincent Guittot
2016-06-22 11:46 ` Peter Zijlstra
2016-06-23 15:35 ` Dietmar Eggemann
2016-06-23 17:15 ` Peter Zijlstra
2016-06-20 14:27 ` Peter Zijlstra
2016-06-23 11:19 ` Peter Zijlstra
2016-08-01 7:30 ` Wanpeng Li
2016-08-01 9:31 ` Mike Galbraith
2016-08-01 9:56 ` Wanpeng Li
2016-08-01 11:52 ` Mike Galbraith
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