Re: [PATCH v2] sched: fix first task of a task group is attached twice

From: Vincent Guittot
Date: Thu May 26 2016 - 04:51:37 EST

On 26 May 2016 at 02:40, Yuyang Du <yuyang.du@xxxxxxxxx> wrote:
> On Thu, May 26, 2016 at 10:26:54AM +0200, Vincent Guittot wrote:
>> On 26 May 2016 at 00:38, Yuyang Du <yuyang.du@xxxxxxxxx> wrote:
>> > On Wed, May 25, 2016 at 05:01:11PM +0200, Vincent Guittot wrote:
>> >> The cfs_rq->avg.last_update_time is initialize to 0 with the main effect
>> >> that the 1st sched_entity that will be attached, will keep its
>> >> last_update_time set to 0 and will attached once again during the
>> >> enqueue.
>> >> Initialize cfs_rq->avg.last_update_time to 1 instead.
>> >
>> > Actually, the first time (attach_task_cfs_rq()) is called even way
>> > before init_entity_runnable_average(), no?
>> maybe there is an issue during the fork of a task too
>> This patch is about the init of the sched_avg of a task group. The
>> problem happens when the 1st task is moved the group but it's not
>> about the fork of a task
> Right, but the root cause is not addressed, which is when forked, the task
> should not be touched on sched avgs before init_entity_runnable_average()
> in wake_up_new_task(). You think?

so yes, this patch doesn't not address the fact that sched avgs should
not be touch before init_entity_runnable_average(). This patch is only
about inti of sched_avg of task group