Messages in this thread | | | Date | Wed, 22 Jun 2011 22:15:15 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch 1/4] sched: Separate the scheduler entry for preemption |
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On Wed, 22 Jun 2011, Jens Axboe wrote:
> On 2011-06-22 20:43, Christoph Hellwig wrote: > > On Wed, Jun 22, 2011 at 05:52:13PM -0000, Thomas Gleixner wrote: > >> Block-IO and workqueues call into notifier functions from the > >> scheduler core code with interrupts and preemption disabled. These > >> calls should be made before entering the scheduler core. > >> > >> To simplify this, separate the scheduler core code into > >> __schedule(). __schedule() is directly called from the places which > >> set PREEMPT_ACTIVE and from schedule(). This allows us to add the work > >> checks into schedule(), so they are only called when a task voluntary > >> goes to sleep. > > > > I don't think that works. We'll need to flush the block requests even > > for an involuntary schedule. > > Yep, doing it just for voluntary schedule() is pointless, since the > caller should just do the flushing on his own. The whole point of the > sched hook was to ensure that involuntary schedules flushed it.
I guess we talk about different things here. The involuntary is when you are preempted, which keeps state unchanged and the current code already excludes that case.
If you block on a mutex, semaphore, completion or whatever that's a different thing. That code calls schedule() not __schedule() and that will flush your stuff as it does now.
Thanks,
tglx
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