Alexis Berlemont wrote: > Hi, > >> the need for a high-level tracing tool constantly increases with the >> growing code base of Xenomai applications. >> >> Yesterday I started a short discussion with Alexis about the status of >> his LTTng combo patch, the Xenomai integration, and the advances of >> LTTng itself. But there are certainly more people interested in this >> topic and may contribute ideas, comments, or even concrete code. >> >> Daniel, you once said that some of your students would start to work on >> this topic. In which domain precisely, more at patch level or rather on >> tools? What is the scheduled beginning and/or deadline for this thesis? >> >> Moreover, does anyone on this list recently tried LTTng on standard >> Linux? Can we consider it reasonably stable and usable? One new thing >> about LTTng internals which Alexis brought up were changes in the custom >> tracing event interface. As this is a rather crucial point with respect >> to the Xenomai instrumentation, we certainly do not want to change it >> back and forth until LTTng stabilises. > > Here is a little quotation from the LTTng Quickstart guide, I used it to > define the LTT events for Xenomai: > > * Add new events to the kernel with genevent > > su - > cd /usr/local/share/LinuxTraceToolkitViewer/facilities > cp process.xml yourfacility.xml > * edit yourfacility.xml to fit your needs. > cd /tmp > /usr/local/bin/genevent > /usr/local/share/LinuxTraceToolkitViewer/facilities/yourfacility.xml > cp ltt-facility-yourfacility.h ltt-facility-id-yourfacility.h \ > /usr/src/linux-2.6.16-lttng-0.x.xx8/include/linux/ltt > cp ltt-facility-loader-yourfacility.c ltt-facility-loader-yourfacility.h \ > /usr/src/linux-2.6.16-lttng-0.x.xx/ltt > * edit the kernel file you want to instrument > - Add #include <linux/ltt/ltt-facility-yourfacility.h> at the beginning > of the file. > - Add a call to the tracing functions. See their names and parameters in > > /usr/src/linux-2.6.16-lttng-0.x.xx/include/linux/ltt/ltt-facility-yourfacility.h > > So, In order to test the combo patch adeos + LTTng I made: > -> I wrote xenomai.xml (cf. attached file) which defines all the Xeno-LTT > events; > -> I used genevent so as to generate the sources and the headers relative > with > my events; > -> Instead of copying them in the kernel, I integrated the sources in > Xenomai. > I was considering that the Xeno events was independant from Linux. > > As a matter of fact, the last point should be rethought as the Xeno build > procedure is now integrated in the kernel.
Not necessarily, you may still compile the nucleus as a module. > > Things are simpler now, we could create an "I-pipe aware LTTng" patch which > could contain : > -> the modifications in Relayfs (for a proper functioning with Adeos); > -> the LTTng core stuff adapted for Adeos (not much work to do on this part); > -> the Xenomai events in include/linux/ltt, and the loading code in ... Hmm, I guess Philippe will not be happy to see Xeno-specific code in the ipipe patch (like I had with my kgdb hack). Is there no clean way to introduce this code together with the Xenomai installation, e.g. when preparing the kernel with the script? > > This patch would be applied after the I-pipe patch (in the same way as the > I-pipe tracer patch). So there would be no need to make combo patches, an > arch-independant additionnal patch would be easier to maintain. > > What do you think of that ? I do not overview every detail (I should actually look at the patch more in detail, but - you know - time...). Everything that helps to reduce maintenance costs while still keeping clean abstraction layers (ipipe is ipipe, xenomai is an independent add-on) is certainly good. > > Eventually, concerning LTTng stabilisation status, I had a look a their > mailing-list (I am lurking on it since the beginning of LTTng) and at their > roadmap: starting from now, their TODO list contains integration and ports, > therefore undertaking an integration of LTTng with Xenomai (rigth now or next > month) does not seem too risky, does it? Sounds good. Sounds at least like they found a stable design we can use now - or soon when resources are available. Jan
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