Messages in this thread Patch in this message | | | Date | Sat, 6 Nov 2021 16:19:26 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting |
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Em Sat, Nov 06, 2021 at 04:09:49PM -0300, Arnaldo Carvalho de Melo escreveu: > Em Fri, Nov 05, 2021 at 01:58:47PM -0700, Namhyung Kim escreveu: > > The current logic for the perf missing feature has a bug that it can > > wrongly clear some modifiers like G or H. Actually some PMUs don't > > support any filtering or exclusion while others do. But we check it > > as a global feature. > > > > For example, the cycles event can have 'G' modifier to enable it only > > in the guest mode on x86. When you don't run any VMs it'll return 0. > > > > # perf stat -a -e cycles:G sleep 1 > > > > Performance counter stats for 'system wide': > > > > 0 cycles:G > > > > 1.000721670 seconds time elapsed > > > > But when it's used with other pmu events that don't support G modifier, > > it'll be reset and return non-zero values. > > > > # perf stat -a -e cycles:G,msr/tsc/ sleep 1 > > > > Performance counter stats for 'system wide': > > > > 538,029,960 cycles:G > > 16,924,010,738 msr/tsc/ > > > > 1.001815327 seconds time elapsed > > > > This is because of the missing feature detection logic being global. > > Add a hashmap to set pmu-specific exclude_host/guest features. > > ⬢[acme@toolbox perf]$ perf test python > 19: 'import perf' in python : FAILED! > ⬢[acme@toolbox perf]$ perf test -v python > Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc > 19: 'import perf' in python : > --- start --- > test child forked, pid 11602 > python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python3' " > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > ImportError: /tmp/build/perf/python/perf.cpython-39-x86_64-linux-gnu.so: undefined symbol: evsel__find_pmu > test child finished with -1 > ---- end ---- > 'import perf' in python: FAILED! > ⬢[acme@toolbox perf]$ > > Trying to fix this now. please do a 'perf test' before submitting > patches.
Added this bandaid, should be good for the time being.
- Arnaldo
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c index 8feef3a05af7b31d..563a9ba8954f31b3 100644 --- a/tools/perf/util/python.c +++ b/tools/perf/util/python.c @@ -69,6 +69,18 @@ void perf_stat__collect_metric_expr(struct evlist *evsel_list) { }
+/* + * This one is needed not to drag the PMU bandwagon, jevents generated + * pmu_sys_event_tables, etc and evsel__find_pmu() is used so far just for + * doing per PMU perf_event_attr.exclude_guest handling, not really needed, so + * far, for the perf python binding known usecases, revisit if this become + * necessary. + */ +struct perf_pmu *evsel__find_pmu(struct evsel *evsel __maybe_unused) +{ + return NULL; +} +
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