On Tue, Mar 11, 2014 at 3:16 PM, Mathieu Desnoyers <[email protected]> wrote: > > > ----- Original Message ----- >> From: "Jérémie Galarneau" <[email protected]> >> To: "zlynus" <[email protected]> >> Cc: "lttng-dev" <[email protected]> >> Sent: Friday, March 7, 2014 1:23:01 PM >> Subject: Re: [lttng-dev] Can tracepoint be listed before app registered? >> >> On Fri, Mar 7, 2014 at 12:26 PM, zlynus <[email protected]> wrote: >> > Hi, >> > Sorry to bother you guys. The lttng-tool man page dosen't make it clear >> > that >> > when the tracepoints of user-space application can be listed. So I did a >> > little test. As far as I can tell ,the tracepoint information is only >> > available during the application is running. >> > >> >> Correct. >> >> > So is it possible that the tracepoint can be available *before* app get >> > running, specifically, before enable-event subcommand? I think it can be >> > quite convenient to output the list when specify which events to trace. If >> > it is not for now, >> > maybe it's a feature worth working on. My idea is lttng-tool could read >> > tracer provider library and get the info,and add a option after 'list' >> > subcommand which let user specify the provider library to read. Just a >> > personal opion from a new comer :-) >> > >> >> You can enable an event before the app is started. However, as you >> pointed out, the session daemon has no knowledge of application events >> before they are launched. >> >> My understanding of your suggestion is that we should define a public >> provider API on which the lttng client could hook itself to list >> events. It would be of limited use in the case of statically linked >> providers, but It's an interesting problem... Do you have a specific >> use-case in mind? > > Another option that would take care of statically linked providers > would be to let a lttng library look at all the executables on the system > (or from a certain path in the system), as well as .so, and list a specific > "tracepoint provider" section that we could specify. We'd need to parse > ELF for this. > > Thoughts ? >
I like the idea. Lingyu, would that be something you'd like to propose as a GSoC project? Regards, Jérémie > Thanks, > > Mathieu > >> >> Regards, >> Jérémie >> >> > Best regards, >> > Lingyu Zhu >> > >> > >> > _______________________________________________ >> > lttng-dev mailing list >> > [email protected] >> > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev >> > >> >> >> >> -- >> Jérémie Galarneau >> EfficiOS Inc. >> http://www.efficios.com >> >> _______________________________________________ >> lttng-dev mailing list >> [email protected] >> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev >> > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com -- Jérémie Galarneau EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
