Re: Accessing sample data (like period) for trace events from python scripts
From: Milian Wolff <hidden>
Date: 2016-08-20 20:31:03
On Freitag, 19. August 2016 10:51:01 CEST Namhyung Kim wrote:
On Fri, Aug 19, 2016 at 10:35:49AM +0900, Namhyung Kim wrote:quoted
On Wed, Aug 17, 2016 at 10:48:31AM +0200, Milian Wolff wrote:quoted
On Wednesday, August 17, 2016 12:05:53 PM CEST Namhyung Kim wrote:quoted
Hi Milian, On Tue, Aug 16, 2016 at 08:42:01PM +0200, Milian Wolff wrote:quoted
Hey all, It doesn't seem to be possible to access the period, tid and various other sample fields from a python (and perl?) script using `perf script`. My use- case would be analyzing a perf data file created by perf inject --sched-stat.I think you can access param_dict["sample"]["period"].No, that is not possible, but would be a viable solution as well.Sorry for late reply. Oh, you wanted to access period of tracepoint but I guess it's always 1, no?OK, it seems sched_stat events have periods bigger than 1. But you can access it using 'runtime' or 'delay' field in the event too. I think sample data of tracepoint event is mostly meaningless and you should access to the event fields for useful information. That's why it doesn't provide the info for tracepoint events, I guess. What do you specifically want to know from sample data?
Using `perf inject --sched-stat`, I can get the sched_stat event period to the sched_switch event (which has the proper backtrace). That is the data I want to access. This is doable when I run: perf script -F event,period But it is not accessible from Perl or Python. Note: the runtime/delay fields are not translated by perf inject, it simply sets the period which is then used by the other perf tools. I really think it should be made possible to access that data from Python/ Perl. Cheers -- Milian Wolff | milian.wolff@kdab.com | Software Engineer KDAB (Deutschland) GmbH&Co KG, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt Experts
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