Messages in this thread | | | Date | Tue, 10 Sep 2013 18:59:57 -0700 | From | Andy Lutomirski <> | Subject | Re: [PATCH 2/7] sched: Add NEED_RESCHED to the preempt_count |
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On 09/10/2013 06:08 AM, Peter Zijlstra wrote: > In order to combine the preemption and need_resched test we need to > fold the need_resched information into the preempt_count value. > > We keep the existing TIF_NEED_RESCHED infrastructure in place but at 3 > sites test it and fold its value into preempt_count; namely: > > - resched_task() when setting TIF_NEED_RESCHED on the current task > - scheduler_ipi() when resched_task() sets TIF_NEED_RESCHED on a > remote task it follows it up with a reschedule IPI > and we can modify the cpu local preempt_count from > there. > - cpu_idle_loop() for when resched_task() found tsk_is_polling().
It looks like the intel_idle code can get confused if TIF_NEED_RESCHED is set but the preempt resched bit is not -- the need_resched call between monitor and mwait won't notice TIF_NEED_RESCHED.
Is this condition possible?
--Andy
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