Messages in this thread | | | Subject | Re: [PATCH] sched: Support current clocksource handling in fallback sched_clock(). | From | Peter Zijlstra <> | Date | Wed, 27 May 2009 08:58:46 +0200 |
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On Tue, 2009-05-26 at 16:00 -0700, john stultz wrote:
> Sure, I guess what I'm trying to pull out here is that should we try to > create some OK_FOR_SCHED_CLOCK flag for clocksources, and then we try to > make this generic so other arches can add that flag and be done, what is > the guidance we want to give to arch maintainers for setting that flag? > > 1) Has to be very very fast. Can we put a number on this? 50ns to read?
I'd express it in cpu cycles, but not sure, the very fastest the arch has :-) Just tell people this is in their scheduling hot-path and they might understand.
> 2) How long does it have to be monotonic for?
Forever? (per cpu)
> Is it ok if it wraps every few seconds?
No, if it wraps it needs to wrap on u64.
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