From mboxrd@z Thu Jan 1 00:00:00 1970 From: milian.wolff@kdab.com (Milian Wolff) Date: Thu, 26 Mar 2020 21:52:57 +0100 Subject: [lttng-dev] LTTng user-space callstacks In-Reply-To: <2022773652.13655.1585251677207.JavaMail.zimbra@efficios.com> References: <2022773652.13655.1585251677207.JavaMail.zimbra@efficios.com> Message-ID: <1834419.usQuhbGJ8B@agathebauer> On Donnerstag, 26. M?rz 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 at kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/pkcs7-signature Size: 3826 bytes Desc: not available URL: