Messages in this thread | | | Subject | Re: [RFC PATCH] sched: Fix sched_wakeup tracepoint | From | Peter Zijlstra <> | Date | Mon, 08 Jun 2015 08:55:30 +0200 |
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On Fri, 2015-06-05 at 13:23 +0000, Mathieu Desnoyers wrote: > sched_wakeup: when try_to_wake_up{,_local} is called in the waker. > sched_activate_task: when the wakee is marked runnable. > sched_switch: when scheduling actually happens. > > We can then calculate wakeup latency as > > time@sched_activate - time@sched_wakeup
One more thing, I think I would disagree with this. I would suggest never to use the 'wakeup' (or 'waking' in my proposal) for timing. I would suggest to use your interrupt tracepoint (or whatever else causes wakeup to be called for this).
The wakeup times should be measured in tasktime -- of course, if interrupts/preemption are disabled then tasktime == walltime.
The scheduling bit OTOH always needs to be measured in walltime, and is most affected by the presence of other tasks on the system.
This too is why I'm not sure it makes sense to combine the two into a single measurement. They should be measured in different time domains.
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