Hi John, On 11.09.23 19:10, John Ogness wrote: > Hi Jan, > > On 2023-09-10, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote: >> is your rtapp tracer [1] somewhere publicly available already? > > No. In fact, it does not yet exist at all. At EOSS2023 I presented a > proposal, mostly to get an initial reaction, feedback, and see if there > was interest from the RT community. > >> And what's the status of this effort? > > Right now I am dedicating my time towards finishing the printk work so > that we can get PREEMPT_RT mainline. I plan on working on an rtapp > tracer after that. If anyone else wants to start this work sooner, I am > happy to contribute where I can. Upstreaming is most important, absolutely. /me neither has the time to start something at this point. But I see the importance of this topic and would like to follow and, where possible, contribute to such an effort. Just recently, I had to explain to colleagues lengthily where traps are when porting applications over -rt. Codifying some of those issues into a runtime checker would definitely be more helpful - though also much harder. > > BTW, it is not yet clear if it should be a tracer or an RV monitor. In > the presentation [2] (starting at 50:15) you can hear Daniel's argument > for implementing this as an RV monitor instead. > > In case you were interested in the bpftrace script I used as a > proof-of-concept, I have attached it to this email. For it to work I > used a Debian/bookworm system (12.0). The kernel package was > linux-image-6.1.0-9-rt-amd64 (6.1.27-1) and the bpftrace package was > version 0.17.0-1. However, in order for bpftrace to support kprobe > offsets, I needed to rebuild the bpftrace package with the extra > Build-Depends "libbfd-dev". As mentioned in the presentation, with any > other kernel binary, the proof-of-concept demo probably won't work. > > Also be aware this was just a proof-of-concept. A real rtapp tracer will > need to catch many more cases (as I mentioned in the presentation). Thanks, Jan > > John Ogness > > [1] https://static.sched.com/hosted_files/eoss2023/27/Proposing%20a%20new%20tracer%20to%20monitor%20RT%20task%20behavior%20-%20John%20Ogness.pdf > > [2] https://www.youtube.com/watch?v=E5cTgiHJKc0 > -- Siemens AG, Technology Linux Expert Center
