Hi Arnaldo, On Thu, Sep 8, 2022 at 11:43 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote: > > Em Wed, Sep 07, 2022 at 11:37:50PM -0700, Namhyung Kim escreveu: > > Hello, > > > > I found that call stack from the lock tracepoint (using bpf_get_stackid) > > can be different on each configuration. For example it's very different > > when I run it on a VM than on a real machine. > > > > The perf lock contention relies on the stack trace to get the lock > > caller names, this kind of difference can be annoying. Ideally we could > > skip stack trace entries for internal BPF or lock functions and get the > > correct caller, but it's not the case as of today. Currently it's hard > > coded to control the behavior of stack traces for the lock contention > > tracepoints. > > > > To handle those differences, add two new options to control the number of > > stack entries and how many it skips. The default value worked well on > > my VM setup, but I had to use --stack-skip=5 on real machines. > > > > You can get it from 'perf/lock-stack-v1' branch in > > > > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > This clashed with a patch you Acked earlier, so lets see if someone has > extra review comments and a v2 become needed for other reason, when you > can refresh it, ok? Sounds good! Thanks, Namhyung
