Messages in this thread | | | Date | Wed, 03 Apr 2013 08:14:20 -0600 | From | David Ahern <> | Subject | Re: [RFC] perf: need to expose sched_clock to correlate user samples with kernel samples |
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On 4/3/13 8:00 AM, Stephane Eranian wrote: >> What's the advantage of changing apps -- like the JIT compiler -- to emit >> perf based timestamps versus having perf emit existing timestamps? ie., >> monotonic and realtime clocks already have vdso mappings for userspace with >> well known performance characteristics. Why not have perf convert its >> perf_clock timestamps into monotonic or realtime when dumping events? >> > Can monotonic timestamps be obtained from NMI context in the kernel?
I don't understand the context of the question.
I am not suggesting perf_clock be changed. I am working on correlating existing perf_clock timestamps to clocks typically used by apps (REALTIME and time-of-day but also applies to MONOTONIC).
You are wanting the reverse -- have apps emit perf_clock timestamps. I was just wondering what is the advantage of this approach?
David
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