Re: [PATCH 1/7] locking/rwsem: don't resched at the end of optimistic spinning

[Peter Zijlstra]

On Sun, Aug 03, 2014 at 10:36:16PM -0400, Waiman Long wrote:
> For a fully preemptive kernel, a call to preempt_enable() could
> potentially trigger a task rescheduling event. In the case of rwsem
> optimistic spinning, the task has either gotten the lock or is going
> to sleep soon. So there is no point to do rescheduling here.

Uh what? Why shouldn't we preempt if we've gotten the lock? What if a
FIFO task just woke up?

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