Am Do., 20. Mai 2021 um 18:25 Uhr schrieb Mathieu Desnoyers <mathieu.desnoy...@efficios.com>: > > ----- On May 20, 2021, at 11:54 AM, Norbert Lange nolang...@gmail.com wrote: > [...] > > >> What prevents you from linking against lttng-ust.so again ? > > > > I did not poke around enough with Lttng to be confident it wont have > > side effects, > > I really don't want it active in production. It doesn't seem there is > > much public knowledge with Xenomai either. > > lttng-ust.so will spawn threads, lttng-ust-tracepoint.so is mostly passive, > > There is indeed a split between instrumentation and runtime threads done > with lttng-ust-tracepoint.so vs lttng-ust.so. > > I understand that this split is missing for tracelog and tracef, and > would be a good thing to have. > > I would be interested to move the tracelog and tracef implementation > from liblttng-ust.so to liblttng-ust-tracepoint.so, even this late > in the -rc cycle, because all users of tracelog/tracef need to link > against liblttng-ust-tracepoint.so anyway. So moving these symbols > should not affect anyone. > > Can you give it a try and let me know if it works for you ?
Will take some time, whats the timeframe you need for feedback? > > So Id want a dynamic tracepoint-provider than i can dlopen (so that > > the signal masks are inherited, > > I hope you dont touch them). > > The signals are all blocked for lttng-ust listener threads. We don't > modify the signal masks in the tracepoint probes. Not sure which is > the target of your question though. The first one, if i'd preloaded lttng-ust and you dont mask signals, then those could end up in the realtime threads. Every Xenomai Thread has a background Linux Thread that's idle when realtime is active, ironically making them perfect targets for signal delivery > > > > > Of course I could just remove all lttng libraries on the production > > system aswell. Still doesnt change that > > tracelog and tracef doesnt work that way. > > Would moving the tracelog/tracef implementation to liblttng-ust-tracepoint.so > solve your issues ? Yes, definitely. They should then work identically to other tracepoints with TRACEPOINT_PROBE_DYNAMIC_LINKAGE. > > > > > I implemented my own tracelog/tracef using the normal lttng > > tracepoints for now, they totally break on source level with 2.13 > > aswell ;) > > is it ok if I do this to access them: > > > > #define TRACEPOINT_DEFINE > > #define TRACEPOINT_PROBE_DYNAMIC_LINKAGE > > // 2.12 > > // #include <lttng/lttng-ust-tracelog.h> > > // #include <lttng/lttng-ust-tracef.h> > > // 2.13 > > #include <lttng/tp/lttng-ust-tracelog.h> > > #include <lttng/tp/lttng-ust-tracef.h> > > > > ie. I would load lttng-ust.so later and can then use those tracepoints. > > Reimplementing the tracelog/tracef providers is not an intended use-case. > I'd very much prefer if we move their implementation to > liblttng-ust-tracepoint.so. FWIW it works, and ill use it for a while (cant just swap out libraries everywhere now). Of course Id love a upstream solution. Norbert _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
