From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Yuyang Du <yuyang.du@intel.com>, Ingo Molnar <mingo@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Benjamin Segall <bsegall@google.com>,
Paul Turner <pjt@google.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Subject: Re: [PATCH v2 2/3] sched/fair: Skip detach and attach new group task
Date: Tue, 31 May 2016 14:39:58 +0200 [thread overview]
Message-ID: <20160531123958.GL3193@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CAKfTPtB-_2yMwkW-nY5c+dBxVTL_zmd4QR=BL13hFr9mHX9B2A@mail.gmail.com>
On Tue, May 31, 2016 at 02:33:45PM +0200, Vincent Guittot wrote:
> The sched_avg of a task is not used anymore in copy_process with
> yuyang's patchset. To be fully correct, we still have a
> p->se.avg.last_update_time = 0 in cpu_cgroup_fork but this is just the
> side effect of factoring cpu_group_fork and cpu_group_move in
> sched_move_task and it will be overwritten by
> init_entity_runnable_average before being used.
Yeah, but why? Why does init_entity_runnable_average() live in
wake_up_new_task()? That doesn't seem to make sense.
Also note that vruntime_normalized() (ab)uses !se->sum_exec_runtime to
detect the new task state.
> Now, cpu_cgroup_fork() only sets task group and cfs_rq of the forked task
>
> copy_process
> sched_fork
> ...
> cgroup_post_fork
> ss->fork() := cpu_cgroup_fork() which only set task group and
> cfs_rq of the sched_entity of the task
>
> wake_up_new_task
> init_entity_runnable_average
> activate_task
> enqueue_task
> attach_task
next prev parent reply other threads:[~2016-05-31 12:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-30 22:32 [PATCH v2 0/3] sched/fair: Skip attach and detach for new group task in task_move_group_fair() Yuyang Du
2016-05-30 22:32 ` [PATCH v2 1/3] sched/fair: Clean up attach_entity_load_avg() Yuyang Du
2016-05-31 8:34 ` Peter Zijlstra
2016-05-31 0:49 ` Yuyang Du
2016-05-31 9:14 ` Peter Zijlstra
2016-05-31 18:37 ` Yuyang Du
2016-05-30 22:32 ` [PATCH v2 2/3] sched/fair: Skip detach and attach new group task Yuyang Du
2016-05-31 11:55 ` Vincent Guittot
2016-05-31 12:03 ` Peter Zijlstra
2016-05-31 12:33 ` Vincent Guittot
2016-05-31 12:39 ` Peter Zijlstra [this message]
2016-05-31 13:20 ` Vincent Guittot
2016-05-30 22:32 ` [PATCH v2 3/3] sched/fair: Add inline to detach_entity_load_evg() Yuyang Du
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