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McKenney writes: > On Thu, Oct 17, 2024 at 03:50:46PM -0700, Ankur Arora wrote: >> Sebastian Andrzej Siewior writes: >> > On 2024-10-15 15:13:46 [-0700], Ankur Arora wrote: >> >> Sebastian Andrzej Siewior writes: >> >> [ ... ] >> Sure. But, that's just begging the question. >> >> We want _NONE and _VOLUNTARY to go away because keeping cond_resched() >> around incurs a cost. > > When you say "go away", do you mean for your use cases? Or globally? When I say "want _ to go away" I mean: cond_resched() is deleterious to performance since you are forced to have code which can do the rescheduling check synchronously -- when this could easily be done asynchronously (as the non voluntary models do). And this either means poor performance (ex. in the page zeroing code where it would be more optimal to work on continguous ranges) or gyrations like the ones that xen_pv_evtchn_do_upcall() and the Xen hypervisor have to go through. And, as we've discussed before, the cond_resched() interface, while it works, is not ideal. Also, a man can dream! -- ankur