Messages in this thread | | | From | Namhyung Kim <> | Date | Mon, 8 Nov 2021 10:53:09 -0800 | Subject | Re: [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting |
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Hi Arnaldo,
On Sat, Nov 6, 2021 at 12:09 PM Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > 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.
Oops, sorry about that. Forgot to run it after the change. I'll check it next time and thanks for the fix.
Thanks, Namhyung
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