Messages in this thread | | | Subject | Re: [RFC] perf: need to expose sched_clock to correlate user samples with kernel samples | From | Pawel Moll <> | Date | Wed, 06 Feb 2013 18:17:42 +0000 |
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On Tue, 2013-02-05 at 22:13 +0000, Stephane Eranian wrote: > The app requesting the timestamp may not necessarily have an active > perf session. And by that I mean, it may not be self-monitoring. But it > could be monitored by an external tool such as perf, without necessary > knowing it.
Fair enough - I guess eg. JIT engine could generate a timestamped information about generated symbols which could be then merged with a stream recorded by the perf tool by yet another tool.
> The timestamp is global or at least per-cpu. It is not tied to a particular > active event.
I know that the implementation does it now, but is it actually specified as such? I could imagine a situation where perf_clock() returns time elapsed since the "current" sys_perf_event_open()... (not that I'd like it ;-)
Paweł
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