* Theodore Tso (tytso@xxxxxxx) wrote: > On Fri, Jan 09, 2009 at 09:49:01AM -0500, Mathieu Desnoyers wrote: > > > > Given this is meant to be in the mainline kernel, using tracepoints > > rather than markers would be more appropriate. Please see > > Documentation/tracepoints.txt and samples/tracepoints/ for details. > > I saw that, but I'm still not sure how I would actually *use* > tracepoints. I can use markers today with Systemtap, and I need an > easy way to be able to selectively do things like "trap and print all > of the logged data when the ext4_request_inode tracepoint/marker is > tripped where dev=='dm-8'". > > Unfortunately, Systemtap seems doomed given its current course and > direction, so I'm not opposed to moving to another solution --- I just > need a HOWTO that demonstrates how I can do this painlessly and > easily; preferably without having me have to manually hack up a kernel > module each time I want to implement the tracing > > Is there an easy way to do that using ltt today? Can you point me at > a sample of how this could be done? > Hi Ted, I just ported LTTng to 2.6.28 yesterday and started doing the port of ext4/jbd2 to tracepoints. As you can see in my 0.74 announcement, the tracepoint work for both jbd2 and ext4 is done. I also did the lttng probe module for jbd2. Now I just have to create the probe module for ext4. I also want to create debugfs files to control per-probe module filtering, e.g. : /mnt/debugfs/ltt/filter/jbd2/dev /mnt/debugfs/ltt/filter/ext4/dev Where writing to it would add device names to the filter list. I would like a scheme where we can easily add/remove devices, list all devices... I think ftrace already has something similar for instrumentation activation. The main question I am facing is : What interface semantic do we want for such filter control file ? Comments/ideas are welcome. Mathieu > - Ted > -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
