Messages in this thread | | | Subject | Re: SCHED: Is task migration necessary in sched_exec(). | From | Peter Zijlstra <> | Date | Wed, 23 Dec 2009 11:53:04 +0100 |
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On Wed, 2009-12-23 at 16:46 +0600, Rakib Mullick wrote: > On 12/23/09, Peter Zijlstra <peterz@infradead.org> wrote: > > On Wed, 2009-12-23 at 16:14 +0600, Rakib Mullick wrote: > > > > > > Well, if there's an imbalance the 'slow' load-balancer will move it > > around eventually anyway, and since it will then have build up a larger > > cache footprint it will be even more expensive. > > > If there is an imbalance - then the overloaded task will moved.
There is no overloaded task, its the runqueue that is overloaded wrt to other runqueues. The load-balancer has to pick a 'random' task and pray. Current heuristics try to pick a task that hasn't been on the cpu for a while, because for those the effective cache footprint is minimal.
> Why the _current_ task?
Because at exec it has effective 0 cache footprint, and is thus an ideal victim to move about.
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