Messages in this thread | | | Date | Mon, 13 Nov 2023 11:10:30 -0500 | Subject | Re: [PATCH] perf evsel: Ignore the non-group case for branch counters | From | "Liang, Kan" <> |
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On 2023-11-13 10:49 a.m., Ian Rogers wrote: > On Thu, Nov 9, 2023 at 8:41 AM <kan.liang@linux.intel.com> wrote: >> >> From: Kan Liang <kan.liang@linux.intel.com> >> >> The perf test 27: Sample parsing fails with the branch counters support >> introduced. >> >> The branch counters feature requires all the events to belong to a >> group. There is no problem with the normal perf usage which usually >> initializes an evlist even for a single evsel. >> But the perf test is special, which may not initialize an evlist. The >> Sample parsing test case is one of the examples. The existing code >> crashes with the !evsel->evlist. >> >> Non-group means the evsel doesn't have branch counters support. > > Thanks Kan, do we need to add this condition to > parse_events__sort_events_and_fix_groups? > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/parse-events.c#n2174 >
I don't think so. The "non-group" here means the case that the evlist is not initialized. It should only happen with some perf test case.
In the parse_events__sort_events_and_fix_groups(), IIUC, the ungrouped event should mean a single event group. The feature works with the case. We don't need to add the condition.
BTW: Arnaldo should have already folded it with the original patch. We don't need the patch anymore. https://lore.kernel.org/lkml/ZU0pGuUBJH+bF1yU@kernel.org/
Thanks, Kan
> Ian > >> Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> >> Closes: https://lore.kernel.org/lkml/ZUv+G+w5EvJgQS45@kernel.org/ >> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> >> --- >> tools/perf/util/evsel.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c >> index 58a9b8c82790..7a6a2d1f96db 100644 >> --- a/tools/perf/util/evsel.c >> +++ b/tools/perf/util/evsel.c >> @@ -2355,6 +2355,10 @@ static inline bool evsel__has_branch_counters(const struct evsel *evsel) >> { >> struct evsel *cur, *leader = evsel__leader(evsel); >> >> + /* The branch counters feature only supports group */ >> + if (!leader || !evsel->evlist) >> + return false; >> + >> evlist__for_each_entry(evsel->evlist, cur) { >> if ((leader == evsel__leader(cur)) && >> (cur->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS)) >> -- >> 2.35.1 >>
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