Messages in this thread | | | Subject | Re: [PATCH] perf parse-events: Use strcmp to compare the PMU name | From | John Garry <> | Date | Thu, 30 Apr 2020 09:54:18 +0100 |
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On 30/04/2020 09:45, Jiri Olsa wrote: > On Thu, Apr 30, 2020 at 08:36:18AM +0800, Jin Yao wrote: >> A big uncore event group is split into multiple small groups which >> only include the uncore events from the same PMU. This has been >> supported in the commit 3cdc5c2cb924a ("perf parse-events: Handle >> uncore event aliases in small groups properly"). >> >> If the event's PMU name starts to repeat, it must be a new event. >> That can be used to distinguish the leader from other members. >> But now it only compares the pointer of pmu_name >> (leader->pmu_name == evsel->pmu_name). >> >> If we use "perf stat -M LLC_MISSES.PCIE_WRITE -a" on cascadelakex, >> the event list is: >> >> evsel->name evsel->pmu_name >> --------------------------------------------------------------- >> unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_4 (as leader) >> unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_2 >> unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_0 >> unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_5 >> unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_3 >> unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_1 >> unc_iio_data_req_of_cpu.mem_write.part1 uncore_iio_4 >> ...... >> >> For the event "unc_iio_data_req_of_cpu.mem_write.part1" with >> "uncore_iio_4", it should be the event from PMU "uncore_iio_4". >> It's not a new leader for this PMU. >> >> But if we use "(leader->pmu_name == evsel->pmu_name)", the check >> would be failed and the event is stored to leaders[] as a new >> PMU leader. >> >> So this patch uses strcmp to compare the PMU name between events. >> >> Fixes: 3cdc5c2cb924a ("perf parse-events: Handle uncore event aliases in small groups properly") >> Signed-off-by: Jin Yao <yao.jin@linux.intel.com> > > looks good, any chance we could have automated test > for this uncore leader setup logic? like maybe the way > John did the pmu-events tests? like test will trigger > only when there's the pmu/events in the system > > Acked-by: Jiri Olsa <jolsa@redhat.com> > > thanks, > jirka
Hi jirka,
JFYI, this is effectively the same patch as I mentioned to you, which was a fix for the same WARN:
https://lore.kernel.org/linux-arm-kernel/1587120084-18990-2-git-send-email-john.garry@huawei.com/
but I found that it "fixed" d4953f7ef1a2 ("perf parse-events: Fix 3 use after frees found with clang ASANutil/parse-events.c"), based on bisect breakage
cheers
> > >> --- >> tools/perf/util/parse-events.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c >> index 10107747b361..786eddb6a097 100644 >> --- a/tools/perf/util/parse-events.c >> +++ b/tools/perf/util/parse-events.c >> @@ -1629,12 +1629,11 @@ parse_events__set_leader_for_uncore_aliase(char *name, struct list_head *list, >> * event. That can be used to distinguish the leader from >> * other members, even they have the same event name. >> */ >> - if ((leader != evsel) && (leader->pmu_name == evsel->pmu_name)) { >> + if ((leader != evsel) && >> + !strcmp(leader->pmu_name, evsel->pmu_name)) { >> is_leader = false; >> continue; >> } >> - /* The name is always alias name */ >> - WARN_ON(strcmp(leader->name, evsel->name)); >> >> /* Store the leader event for each PMU */ >> leaders[nr_pmu++] = (uintptr_t) evsel; >> -- >> 2.17.1 >> > > . >
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