Hmm, I don't know unfortunately, it should be checked Best regards, Valentin Grigorev On Fri, Mar 27, 2020 at 4:55 PM Mathieu Desnoyers < mathieu.desnoyers@efficios.com> wrote: > Last time I checked, the main issue with perf's handling of cases that > lack frame pointers > is that they grab a ~2-4kB worth of stack data into the trace, and then > post-process it > with libunwind. This might be OK for sampling use-cases, but is not > something I consider > appropriate for tracing due to considerably increased use of tracing > throughput. > > Has the situation changed on the perf side ? > > Thanks, > > Mathieu > > ----- On Mar 27, 2020, at 9:44 AM, Valentin Grigorev < > valentin.grigorev@jetbrains.com> wrote: > > Yeah, as far as I know, perf [1] is successfully using libunwind to > provide callstacks. Probably, LTTng team should think about it too, if > there are no serious obstacles. > > [1]: https://perf.wiki.kernel.org/index.php/Main_Page > > > Best regards, > Valentin Grigorev > > > On Thu, Mar 26, 2020 at 11:53 PM Milian Wolff > wrote: > >> On Donnerstag, 26. März 2020 20:41:17 CET Mathieu Desnoyers via lttng-dev >> wrote: >> > ----- On Mar 26, 2020, at 1:39 PM, lttng-dev >> >> wrote: >> > > Hello! >> > > >> > > Currently, callstack collection in LTTng is only available for >> > > kernel-space >> > > events with context fields callstack-kernel and callstack-user . >> > > >> > > Is it expected that callstack collection for LTTng-UST will be added >> too? >> > > And if it is expected, then how soon? >> > >> > Hi Valentin, >> > >> > It is something that would be interesting and useful, but a lot of work >> > would be needed to have stack-walking this is fast enough and reentrant >> wrt >> > signal handlers. Unfortunately, the backtrace(3) functions do not meet >> > those requirements. >> > >> > Also, for gathering user-space callstacks from the kernel tracer, it >> only >> > works if all user-space is compiled with frame pointers. This is also a >> > limitation that would require a lot of work to overcome neatly. >> > >> > None of those features are currently on any roadmap due to lack of >> customers >> > showing interest in getting this done. >> >> libunwind [1] should meet the requirements you need. It is high >> performance >> thanks to extensive caching, signal safe and does not rely on frame >> pointers. >> >> [1]: https://github.com/libunwind/libunwind >> >> -- >> Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer >> KDAB (Deutschland) GmbH, a KDAB Group company >> Tel: +49-30-521325470 >> KDAB - The Qt, C++ and OpenGL Experts > > > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com >