Messages in this thread | | | Subject | Re: [PATCH v2] sched/fair: Fix enqueue_task_fair warning some more | From | Dietmar Eggemann <> | Date | Mon, 11 May 2020 19:03:22 +0200 |
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Hi Tao,
On 11/05/2020 17:44, Tao Zhou wrote: > Hi Dietmar,
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> On Mon, May 11, 2020 at 12:39:52PM +0200, Dietmar Eggemann wrote: >> On 11/05/2020 11:36, Vincent Guittot wrote: >>> On Mon, 11 May 2020 at 10:40, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: >>>> >>>> On 08/05/2020 19:02, Tao Zhou wrote: >>>>> On Fri, May 08, 2020 at 05:27:44PM +0200, Vincent Guittot wrote: >>>>>> On Fri, 8 May 2020 at 17:12, Tao Zhou <zohooouoto@zoho.com.cn> wrote: >>>>>>> >>>>>>> Hi Phil, >>>>>>> >>>>>>> On Thu, May 07, 2020 at 04:36:12PM -0400, Phil Auld wrote: >>>>>>>> sched/fair: Fix enqueue_task_fair warning some more
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>> I don't grasp how can cfs_a->on_list=1, when cfs_a is throttled and >> cfs_b, cfs_c are in a throttled hierarchy? > > I remember that Vincent explained that in this thread: > > https://lore.kernel.org/lkml/CAKfTPtDxE32RrTusYTBUcwYoJFvadLLaMUp7gOsXdj_zQcaWdA@mail.gmail.com/ > > This was what I confused also. When enqueue one task, the throttled > cfs_rq may be added back to the leaf_cfs_rq list.
As long as we only consider one hierarchy than I can't see how we can enqueue a task and hit cfs_a->on_list=1 on a throttled cfs_a.
But there might be a cfs_b' (another child of cfs_a) sub hierarchy which had a task enqueue just before and this set cfs_a->on_list=1.
Tried to read the email you pointed at carefully but can't see it there ... pretty tired right now, maybe tomorrow?
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