On Montag, 28. September 2015 23:08:39 CEST Milian Wolff wrote: > On Montag, 28. September 2015 19:12:27 CEST Milian Wolff wrote: > > Hey all, > > > > This was asked before, but I still cannot find any good documentation on > > the matter. How does one access the callgraph from a python script > > generated by perf script? The export-to-postgresql.py seems to indicate > > that this feature was added, but the code is too convoluted for me to > > grasp. > > > > Looking at the code for trace-event-python.c I see that there is a > > common_callchain, but I don't get such code generate: > > > > perf record --call-graph dwarf kwrite > > perf script -g python > > > > the result is: https://paste.kde.org/p0uazuubi > > > > Note how the `while ((event = trace_find_next_event(pevent, event)))` loop > > has not triggered any output. The reason is that pevent is NULL - where is > > that supposed to be set when looking at builtin-script.c? > > > > Can someone explain me what I'm doing wrong? Can someone reproduce the odd > > behavior above? > > OK, so it seems the above only cares for trace points, as the name suggests. > I.e. it works for files where I trace e.g. -e syscalls:sys_enter_open. > > Why is it not possible to script perf for data obtained from counters? I'd > hoped to use that to convert the perf output to callgrind format, in order > to open it with kcachegrind. > > Considering that `perf script` without any arguments prints out all the > required information, I can of course write a wrapper script around it, but > using it directly would have been much better.
Studying the code further I stumbled upon process_event which seems to do what I want. At least that function get a dict with all information, including callchain, and also works with perf data files obtained from a counter. Could someone please document that? Thanks -- Milian Wolff | [email protected] | Software Engineer KDAB (Deutschland) GmbH&Co KG, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt Experts
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