On Wed, May 15, 2024 at 9:20 PM Ian Rogers <irogers@xxxxxxxxxx> wrote: > > Allow uid and gid to be terms in BPF filters by first breaking the > connection between filter terms and PERF_SAMPLE_xx values. Calculate > the uid and gid using the bpf_get_current_uid_gid helper, rather than > from a value in the sample. Allow filters to be passed to perf top, this allows: > > $ perf top -e cycles:P --filter "uid == $(id -u)" > > to work as a "perf top -u" workaround, as "perf top -u" usually fails > due to processes/threads terminating between the /proc scan and the > perf_event_open. Fwiw, something I noticed playing around with this (my workload was `perf test -w noploop 100000` as different users) is that old samples appeared to linger around making terminated processes still appear in the top list. My guess is that there aren't other samples showing up and pushing the old sample events out of the ring buffers due to the filter. This can look quite odd and I don't know if we have a way to improve upon it, flush the ring buffers, histograms, etc. It appears to be a latent `perf top` issue that you could encounter on other low frequency events, but I thought I'd mention it anyway. Thanks, Ian > Ian Rogers (3): > perf bpf filter: Give terms their own enum > perf bpf filter: Add uid and gid terms > perf top: Allow filters on events > > tools/perf/Documentation/perf-record.txt | 2 +- > tools/perf/Documentation/perf-top.txt | 4 ++ > tools/perf/builtin-top.c | 9 +++ > tools/perf/util/bpf-filter.c | 55 ++++++++++++---- > tools/perf/util/bpf-filter.h | 5 +- > tools/perf/util/bpf-filter.l | 66 +++++++++---------- > tools/perf/util/bpf-filter.y | 7 +- > tools/perf/util/bpf_skel/sample-filter.h | 27 +++++++- > tools/perf/util/bpf_skel/sample_filter.bpf.c | 67 +++++++++++++++----- > 9 files changed, 172 insertions(+), 70 deletions(-) > > -- > 2.45.0.rc1.225.g2a3ae87e7f-goog >
