Messages in this thread | | | Subject | Re: Q: sched_clock() vs. clocksource, how to implement correctly | From | Daniel Walker <> | Date | Mon, 26 Apr 2010 16:48:14 -0700 |
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On Fri, 2010-04-23 at 18:29 +0200, Martin Schwidefsky wrote: > > Questions: > > > > - Isn't sched_clock() supposed to be extended to 64bit so > > that it practically never wraps? > > (old implementations use cnt32_to_63()) > > Yes, sched_clock() is supposed to return a monotonic timestamp. > > > - What would be the effect on scheduling when sched_clock() wraps? > > It would confuse the process accounting and the scheduling I guess. >
Are you sure about this? I'm pretty sure I've seen Ingo say multiple times that sched_clock can wrap, and can be unstable. For instance sched_clock is (was?) directly connected to the TSC on x86 ..
If it really can't wrap there must bunches of architectures that would need to be fixed up.
Daniel
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