----- Original Message ----- > From: "David Goulet" <dgou...@efficios.com> > To: "Jan Glauber" <jan.glau...@gmail.com> > Cc: lttng-dev@lists.lttng.org > Sent: Monday, April 14, 2014 8:40:51 PM > Subject: Re: [lttng-dev] [RFC Patch Tools 0/4] Configurable lttng-probe > modules > > On 11 Apr (10:40:47), Jan Glauber wrote: > > On Thu, Apr 10, 2014 at 03:45:51PM -0400, David Goulet wrote: > > > On 03 Apr (12:57:43), Jan Glauber wrote: > > > > Hi LTTng'ers, > > > > > > > > I've asked briefly for the configurable probes feature at the Tracing > > > > summit, > > > > here is an RFC how we could implement it. > > > > > > > > Why I want to have this feature: > > > > Currently the LTTng probes that are loaded when a session is created > > > > are defined > > > > in a static list. If the user wants to change the loaded probes (for > > > > instance > > > > disable the very noisy rcu) then lttng-tools must be recompiled or the > > > > modules must > > > > be blacklisted or deleted. I also found that in our embedded > > > > environment the default > > > > busybox configuration is to disable the blacklist feature, so > > > > blacklisting is not an > > > > option. > > > > > > > > Therefore I want to have a more flexible way of defining which probes > > > > to load > > > > on session start. We could use an environment variable that (if > > > > present) > > > > overrides the default and only loads the probes named in the variable. > > > > > > > > Patch 1 is a cleanup and patch 2 & 3 are preparation for the feature in > > > > patch 4. > > > > Please review and give feedback if this approach is feasible. > > > > > > Hi Jan, > > > > > > First of all, thanks for this! Except some syntax issue, this looks > > > great! Sorry took a while to respond, busy busy improving lttng :P. > > > > Hi David, > > > > thanks for reviewing! Also, I hope part of the improvement work was to > > decide > > on the name for the 2.5 release ;- > > Always a priority! :P > > > > > > Before we go further in mergin this, I see you took the approach of > > > adding an env. variable to provide the list of probes you want to load. > > > Right now in the upstream master (for 2.5), we have the support for a > > > configuration file for lttng-sessiond. Could it be a way you would > > > prefer (or use) instead of env. var? I understand that embedded stuff, a > > > conf file might not be preferable. > > > > Actually a config file was my first thought also, but I only found the > > .lttngrc > > which is generated when a session is started. Where is the sessiond config > > file > > located? I don't see a config file under /etc or in the home directory. > > As of now, you have to pass it to the daemon: > > -f --config Load daemon configuration file > > For 2.5, we want to have a default config. file installed in /etc/lttng/ > and provide also documentation on it with probably a man page. > > We went with the INI file format so in our case here I can see a simple > option like: > > modules = probe1, probe2, probe3, ... > > and by default load ALL. > > > > > > Anyhow, I'm comfortable merging this and adding this env. var but an > > > option in the configuration file could also be awesome! :) > > > > > > One thing that would be great if you have a minute, is to send me a > > > patch for the man page update of that new variable. > > > > I'll do that when we've decided about config file vs. env variable... > > Yeah to be thorough, we should have an ENV. variable, command line > option and config option. ENV overrides cmdline which overrides config.
Did you rather mean: - environment variables override config. - cmdline options override environment variables and config, Thanks, Mathieu > > For now, I'm OK merging your patches but having at least the > configuration option in the config file for 2.5 would be very > appreciated. > > Cheers! > David > > > > > --Jan > > > > > > > Cheers! > > > David > > > > > > > > > > > thanks, > > > > Jan > > > > --- > > > > Harman Becker Automotive GmbH > > > > System Profiling & Optimizing Team > > > > > > > > > > > > Jan Glauber (4): > > > > Use common functions for module loading and unloading > > > > Seperate probe modules from control modules > > > > Remove required parameter from module parameters > > > > Dynamic probe list support > > > > > > > > src/bin/lttng-sessiond/kern-modules.h | 3 +- > > > > src/bin/lttng-sessiond/modprobe.c | 292 > > > > ++++++++++++++++++--------------- > > > > src/common/defaults.h | 3 + > > > > src/common/utils.c | 10 ++ > > > > src/common/utils.h | 1 + > > > > 5 files changed, 172 insertions(+), 137 deletions(-) > > > > > > > > -- > > > > 1.7.9.5 > > > > > > > > > > > > _______________________________________________ > > > > lttng-dev mailing list > > > > lttng-dev@lists.lttng.org > > > > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > > > > > > _______________________________________________ > lttng-dev mailing list > lttng-dev@lists.lttng.org > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev