Messages in this thread | | | Subject | Re: [PATCH 1/2] sched: allow SCHED_BATCH to preempt SCHED_IDLE tasks | From | Mike Galbraith <> | Date | Wed, 23 Feb 2011 06:31:58 +0100 |
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On Wed, 2011-02-23 at 05:20 +0100, Mike Galbraith wrote: > On Tue, 2011-02-22 at 13:04 -0800, Darren Hart wrote: > > Perform the test for SCHED_IDLE before testing for SCHED_BATCH (and ensure idle > > tasks don't preempt idle tasks) so the non-interactive, but still important, > > SCHED_BATCH tasks will run in favor of the very low priority SCHED_IDLE tasks. > > Yeah, that could be construed as a fairness fix for light SCHED_BATCH vs > a heavy SCHED_IDLE. It should lower latencies for both when mixed.
Hm. Seems SCHED_IDLE _always_ being preempted is a potential terminal starvation bug though, unless preempt_tick() checks spread to guarantee that the preempted task will eventually get the CPU back, even in the face of massive non-idle wakeup driven load.. which it does not. (idle task holds resource?)
Maybe my imagination has had too much java though.
-Mike
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