Messages in this thread | | | Date | Mon, 13 Dec 2010 11:01:13 -0700 | From | "David S. Ahern" <> | Subject | Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header |
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On 12/13/10 10:57, Peter Zijlstra wrote: >> What about creating a PERF_RECORD_TIME and generate an event when the >> counter is opened? It contains a PERF_SAMPLE_TIME and say >> PERF_SAMPLE_TOD (time-of-day)? We're not sending rockets to saturn; we >> just need the timestamps to match other log files. > > That's similar to the first thing I proposed. The problem is with long > record sessions your drift can become quite significant, then when you > merge sort your other log events stuff can get out of order. Which can > lead to some serious head-scratching..
Gotcha. Missed that in the flury of emails.
Arnaldo: Are you ok with this option? This should append mode as well.
> > Another problem with this approach is things like flight-recorder mode > where you constantly over-write your old data, you'd have to build some > trigger to always output a new record before you over-write the old one, > so there's always one consistent record around. Drift is an even more > serious problem here since flight-record more could be running for days > before (if ever) you dump it.
Ok. I was not aware flight-recorder mode was an option today.
David
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