Re: [PATCH][2.5] Don't schedule tasks on offline cpus

From: Zwane Mwaikambo (zwane@holomorphy.com)
Date: Mon Feb 17 2003 - 09:47:40 EST


On Mon, 17 Feb 2003, Ingo Molnar wrote:

>
> On Mon, 17 Feb 2003, Zwane Mwaikambo wrote:
>
> > We don't want to allow a cpu going offline to keep doing scheduler work
> > so let it exit early, otherwise we'd keep pulling in tasks every timer
> > tick.
>
> i'd rather have all the hotplug CPU code to do this kind of stuff
> completely out of line. Start up a max-RT-priority housekeeping task and
> just clean the runqueue and deregister the CPU in one atomic pass - look
> at how the migration threads do similar stuff. No need to contaminate
> various codepaths with 'is this CPU online' checks.

Ok for this we'll have to move the task migration down till after the cpu
has gone completely offline ie dead, then pull the tasks off the dead
runqueue. I'm not aware of any ill effects of such a move.

        Zwane

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