Messages in this thread | | | Date | Tue, 4 Nov 2014 16:23:45 +0800 | From | Wanpeng Li <> | Subject | Re: [PATCH RFC] sched/deadline: support dl task migrate during cpu hotplug |
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Hi Peter, On Tue, Nov 04, 2014 at 09:32:25AM +0100, Peter Zijlstra wrote: >On Tue, Nov 04, 2014 at 07:57:48AM +0800, Wanpeng Li wrote: >> On Mon, Nov 03, 2014 at 11:41:11AM +0100, Peter Zijlstra wrote: > >> >On Fri, Oct 31, 2014 at 03:28:17PM +0800, Wanpeng Li wrote: >> >So what is wrong with making dl_task_timer() deal with it? The timer >> >will still fire on the correct time, canceling it and or otherwise >> >messing with the CBS is wrong. Once it fires, all we need to do is >> >migrate it to another cpu (preferably one that is still online of course >> >:-). > >> Do you mean what I need to do is push the task to another cpu in dl_task_timer() >> if rq is offline? > >That does indeed appear to be the sensible fix to me. > >> In addition, what will happen if dl task can't preempt on >> another cpu? > >So if we find that the rq the task was on is no longer available, we >need to select a new rq, the 'right' rq would be the one running the >latest deadline. > >If it cannot preempt the latest (running) deadline, it was not eligible >for running in the first place so no worries, right?
I think this will lead to this deadline task cannot running on any rqs any more. If my understanding is not right, when it will be picked?
Regards, Wanpeng Li
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