Re: Accessing sample data (like period) for trace events from python scripts

[Milian Wolff <milian.wolff@kdab.com>]

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On Wednesday, August 17, 2016 12:05:53 PM CEST Namhyung Kim wrote:
> Hi Milian,
> 
> On Tue, Aug 16, 2016 at 08:42:01PM +0200, Milian Wolff wrote:
> > 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.

~~~~~~~~~~~~~~~~~~
/tmp$ cat perf-script.py

import os
import sys

sys.path.append(os.environ['PERF_EXEC_PATH'] + \
        '/scripts/python/Perf-Trace-Util/lib/Perf/Trace')

from perf_trace_context import *
from Core import *

def trace_unhandled(event_name, context, event_fields_dict):
        print event_fields_dict['sample']['period']

/tmp$ perf script -s perf-script.py
Traceback (most recent call last):
  File "perf-script.py", line 11, in trace_unhandled
    print event_fields_dict['sample']['period']
KeyError: 'sample'
Fatal Python error: problem in Python trace event handler
Aborted (core dumped)
~~~~~~~~~~~~~~~~~~

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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