lkml.org 
[lkml]   [2013]   [Apr]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] perf: need to expose sched_clock to correlate user samples with kernel samples
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



\
 
 \ /
  Last update: 2013-04-04 00:41    [W:0.803 / U:0.280 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site