Messages in this thread Patch in this message | | | From | Jin Yao <> | Subject | [PATCH] perf evlist: Ensure grouped events with same cpu map | Date | Thu, 21 May 2020 14:22:40 +0800 |
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A metric may consist of core event and uncore event (or other per-socket event)
For example, the metric "C2_Pkg_Residency" consists of "cstate_pkg/c2-residency" and "msr/tsc". The former is per-socket event and the latter is per-cpu event.
"C2_Pkg_Residency" hits assertion failure on cascadelakex.
# perf stat -M "C2_Pkg_Residency" -a -- sleep 1 perf: util/evsel.c:1464: get_group_fd: Assertion `!(fd == -1)' failed. Aborted
The root cause is one issue in get_group_fd(), access violation!
For a group mixed with per-socket event and per-cpu event and the group leader is per-socket event, access violation will happen.
perf_evsel__alloc_fd allocates one FD member for per-socket event. Only FD(evsel, 0, 0) is valid (suppose one-socket system).
But for per-cpu event, perf_evsel__alloc_fd allocates N FD members (N = ncpus). For example, if ncpus is 8, FD(evsel, 0, 0) to FD(evsel, 7, 0) are valid.
get_group_fd(struct evsel *evsel, int cpu, int thread) { struct evsel *leader = evsel->leader;
fd = FD(leader, cpu, thread); /* access violation */ }
If leader is per-socket event, only FD(leader, 0, 0) is valid. So when get_group_fd tries to access FD(leader, 1, 0), access violation will happen.
This patch ensures that the grouped events with same cpu maps before we go to get_group_fd.
If the cpu maps are not matched, we force to disable the group.
Fixes: 6a4bb04caacc8 ("perf tools: Enable grouping logic for parsed events") Signed-off-by: Jin Yao <yao.jin@linux.intel.com> --- tools/perf/builtin-stat.c | 3 +++ tools/perf/util/evlist.c | 32 ++++++++++++++++++++++++++++++++ tools/perf/util/evlist.h | 5 +++++ 3 files changed, 40 insertions(+)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 377e575f9645..0e4fc6b3323c 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -584,6 +584,9 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx) if (affinity__setup(&affinity) < 0) return -1; + if (!evlist__cpus_matched(evsel_list)) + evlist__force_disable_group(evsel_list); + evlist__for_each_cpu (evsel_list, i, cpu) { affinity__set(&affinity, cpu); diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 2a9de6491700..fc6e410ca63b 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -1704,3 +1704,35 @@ struct evsel *perf_evlist__reset_weak_group(struct evlist *evsel_list, } return leader; } + +bool evlist__cpus_matched(struct evlist *evlist) +{ + struct evsel *prev = evlist__first(evlist), *evsel = prev; + + if (prev->core.nr_members <= 1) + return true; + + evlist__for_each_entry_continue(evlist, evsel) { + if (evsel->core.cpus->nr != prev->core.cpus->nr) + return false; + + for (int i = 0; i < evsel->core.cpus->nr; i++) { + if (evsel->core.cpus->map[i] != prev->core.cpus->map[i]) + return false; + } + + prev = evsel; + } + + return true; +} + +void evlist__force_disable_group(struct evlist *evlist) +{ + struct evsel *evsel; + + evlist__for_each_entry(evlist, evsel) { + evsel->leader = evsel; + evsel->core.nr_members = 0; + } +} diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index b6f325dfb4d2..ea7a53166cbd 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -355,4 +355,9 @@ void perf_evlist__force_leader(struct evlist *evlist); struct evsel *perf_evlist__reset_weak_group(struct evlist *evlist, struct evsel *evsel, bool close); + +bool evlist__cpus_matched(struct evlist *evlist); + +void evlist__force_disable_group(struct evlist *evlist); + #endif /* __PERF_EVLIST_H */ -- 2.17.1
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