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. 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 [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
