On Thu, Jan 15, 2009 at 08:44:03AM +0100, Peter Zijlstra wrote: > On Thu, 2009-01-15 at 01:46 +0100, Nick Piggin wrote: > > > Hmm, well this is rather a slow path, I would say. I'd prefer not to > > modify schedule in this way (if we just get scheduled back on after > > being switched away, the subsequent call to schedule is going to be > > cache hot and not do too much work). > > > > preempt_enable_noresched maybe if you really care, would close up the > > window even more. But is it really worthwhile? We'd want to see numbers > > (when in doubt, keep it simpler). > > I initially did the preempt_enable_no_resched() thing and that showed > some improvement for PREEMPT=y kernels (lost the numbers though). > > When I redid all the patches I tried closing that last hole by doing > that __schedule() thing, never realizing that schedule() would then get > extra overhead,.. d'0h. > > I agree that that isn't worth it. I shall revert to > preempt_enable_no_resched() and try to get some new numbers.
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