Hi, On Thu, Apr 05, 2018 at 11:17:57AM +0200, aleix wrote: > Hello List! This is my first message here :)
Welcome! > > I would like to share my experience playing with Kernel lock > instrumentation, LTTng and Trace Compass which might be useful for > others when analyzing applications behavior. Before going further, you might want to repost this on the Tracecompass mailing list: https://accounts.eclipse.org/mailing-list/tracecompass-dev They are most likely interested by all of this. > > Currently, the Linux kernel features a set of lock tracepoints which > track lock acquisition and contention [1]: > > - lock_acquire > - lock_acquired > - lock_contended > - lock_release > > However, the current version of LTTng does not instrument this > tracepoints (the code is in the source code but commented [2]). The > guys on LTTng IRC helped me enabling them again by just uncommenting > the code. > ... > > Hence, what I would like to point out is how useful it has been for me > to enable the LTTng lock tracepoints. I think it would be great if > they could be added back again into mainland. Given your current use case, it make a compelling point toward spending some time investigating the possibility of making those tracepoints accessible. Would you mind creating a bug here [1] regarding this so we can track it in the future? [1] https://bugs.lttng.org/projects/lttng-modules/ > If this can be done, I > think it woulde make sense to propose the Trace Compass people to > include a kernel lock view. > > It looks like the lock events are by far the most frequent events, > quickly filling LTTng buffers. However, they are only generated if the > kernel is compiled with CONFIG_LOCK_STAT so this should not annoy the > unaware user. > > I hope my experience is of help! Thanks a lot for your work! :D Absolutely, we are always interested in how our tools are used in the wild. Thanks for sharing. > > [1] See Documentation/locking/lockstat.txt on the Linux Kernel source > for more information. > [2] As Compudj pointed out, the reason is found in this conversation: > https://lists.lttng.org/pipermail/lttng-dev/2012-December/019256.html -- Jonathan Rajotte-Julien EfficiOS _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
