Messages in this thread | | | From | John Garry <> | Subject | Re: [RFC PATCH 1/1] perf arm64: Implement --topdown with metrics | Date | Wed, 15 Dec 2021 10:52:25 +0000 |
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Hi Andrew,
>> const struct pmu_event *metricgroup__find_metric(const char *metric, >> const struct pmu_events_map *map); >> int metricgroup__parse_groups_test(struct evlist *evlist, >> diff --git a/tools/perf/util/topdown.c b/tools/perf/util/topdown.c >> index 1081b20f9891..57c0c5f2c6bd 100644 >> --- a/tools/perf/util/topdown.c >> +++ b/tools/perf/util/topdown.c >> @@ -56,3 +56,9 @@ __weak bool arch_topdown_sample_read(struct evsel *leader __maybe_unused) >> { >> return false; >> } >> + >> +__weak bool arch_topdown_use_json_metrics(void) >> +{
AFAICS, only x86 supports topdown today and that is because they have special kernel topdown events exposed for the kernel CPU PMU driver. So other architectures - not only arm - would need rely on metricgroups for topdown support. So let's make this generic for all archs.
> I like this extension! I've ranted in the past about weak symbols > breaking with archives due to lazy loading [1]. In this case > tools/perf/arch/arm64/util/topdown.c has no other symbols within it > and so the weak symbol has an extra chance of being linked > incorrectly. We could add a new command line of --topdown-json to > avoid this, but there seems little difference in doing this over just > doing '-M TopDownL1'.
> Is it possible to use the json metric approach > for when the CPU version fails?
I think that's a good idea.
In addition we could also add a --topdown arg to force using JSON metricgroups.
Did you actually test this patch? I have something experimental working from some time ago, and it was more complicated than this. I need to check the code again...
Thanks, John
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