sched: fair scheduler should not resched rt tasks

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With use of ftrace Steven noticed that some RT tasks got rescheduled due
to sched_fair interaction.

What happens is that we reprogram the hrtick from enqueue/dequeue_fair_task()
because that can change nr_running, and thus a current tasks ideal runtime.
However, its possible the current task isn't a fair_sched_class task, and thus
doesn't have a hrtick set to change.

Fix this by wrapping those hrtick_start_fair() calls in a hrtick_update()
function, which will check for the right conditions.

Reported-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

...

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Peter Zijlstra 2008-10-17 19:27:03 +02:00 • committed by Ingo Molnar

parent ffda12a17a

commit a4c2f00f5c

1 changed files with 24 additions and 4 deletions

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kernel/sched_fair.c

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