Messages in this thread | | | Date | Tue, 17 May 2022 09:43:28 -0400 | Subject | Re: [PATCH V2 1/4] perf evsel: Fixes topdown events in a weak group for the hybrid platform | From | "Liang, Kan" <> |
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On 5/16/2022 10:52 PM, Ian Rogers wrote: > On Mon, May 16, 2022 at 8:25 AM <kan.liang@linux.intel.com> wrote: >> >> From: Kan Liang <kan.liang@linux.intel.com> >> >> The patch ("perf evlist: Keep topdown counters in weak group") fixes the >> perf metrics topdown event issue when the topdown events are in a weak >> group on a non-hybrid platform. However, it doesn't work for the hybrid >> platform. >> >> $./perf stat -e '{cpu_core/slots/,cpu_core/topdown-bad-spec/, >> cpu_core/topdown-be-bound/,cpu_core/topdown-fe-bound/, >> cpu_core/topdown-retiring/,cpu_core/branch-instructions/, >> cpu_core/branch-misses/,cpu_core/bus-cycles/,cpu_core/cache-misses/, >> cpu_core/cache-references/,cpu_core/cpu-cycles/,cpu_core/instructions/, >> cpu_core/mem-loads/,cpu_core/mem-stores/,cpu_core/ref-cycles/, >> cpu_core/cache-misses/,cpu_core/cache-references/}:W' -a sleep 1 >> >> Performance counter stats for 'system wide': >> >> 751,765,068 cpu_core/slots/ (84.07%) >> <not supported> cpu_core/topdown-bad-spec/ >> <not supported> cpu_core/topdown-be-bound/ >> <not supported> cpu_core/topdown-fe-bound/ >> <not supported> cpu_core/topdown-retiring/ >> 12,398,197 cpu_core/branch-instructions/ (84.07%) >> 1,054,218 cpu_core/branch-misses/ (84.24%) >> 539,764,637 cpu_core/bus-cycles/ (84.64%) >> 14,683 cpu_core/cache-misses/ (84.87%) >> 7,277,809 cpu_core/cache-references/ (77.30%) >> 222,299,439 cpu_core/cpu-cycles/ (77.28%) >> 63,661,714 cpu_core/instructions/ (84.85%) >> 0 cpu_core/mem-loads/ (77.29%) >> 12,271,725 cpu_core/mem-stores/ (77.30%) >> 542,241,102 cpu_core/ref-cycles/ (84.85%) >> 8,854 cpu_core/cache-misses/ (76.71%) >> 7,179,013 cpu_core/cache-references/ (76.31%) >> >> 1.003245250 seconds time elapsed >> >> A hybrid platform has a different PMU name for the core PMUs, while >> the current perf hard code the PMU name "cpu". >> >> The evsel->pmu_name can be used to replace the "cpu" to fix the issue. >> For a hybrid platform, the pmu_name must be non-NULL. Because there are >> at least two core PMUs. The PMU has to be specified. >> For a non-hybrid platform, the pmu_name may be NULL. Because there is >> only one core PMU, "cpu". For a NULL pmu_name, we can safely assume that >> it is a "cpu" PMU. >> >> In case other PMUs also define the "slots" event, checking the PMU type >> as well. >> >> With the patch, >> >> $perf stat -e '{cpu_core/slots/,cpu_core/topdown-bad-spec/, >> cpu_core/topdown-be-bound/,cpu_core/topdown-fe-bound/, >> cpu_core/topdown-retiring/,cpu_core/branch-instructions/, >> cpu_core/branch-misses/,cpu_core/bus-cycles/,cpu_core/cache-misses/, >> cpu_core/cache-references/,cpu_core/cpu-cycles/,cpu_core/instructions/, >> cpu_core/mem-loads/,cpu_core/mem-stores/,cpu_core/ref-cycles/, >> cpu_core/cache-misses/,cpu_core/cache-references/}:W' -a sleep 1 >> >> Performance counter stats for 'system wide': >> >> 766,620,266 cpu_core/slots/ (84.06%) >> 73,172,129 cpu_core/topdown-bad-spec/ # 9.5% bad speculation (84.06%) >> 193,443,341 cpu_core/topdown-be-bound/ # 25.0% backend bound (84.06%) >> 403,940,929 cpu_core/topdown-fe-bound/ # 52.3% frontend bound (84.06%) >> 102,070,237 cpu_core/topdown-retiring/ # 13.2% retiring (84.06%) >> 12,364,429 cpu_core/branch-instructions/ (84.03%) >> 1,080,124 cpu_core/branch-misses/ (84.24%) >> 564,120,383 cpu_core/bus-cycles/ (84.65%) >> 36,979 cpu_core/cache-misses/ (84.86%) >> 7,298,094 cpu_core/cache-references/ (77.30%) >> 227,174,372 cpu_core/cpu-cycles/ (77.31%) >> 63,886,523 cpu_core/instructions/ (84.87%) >> 0 cpu_core/mem-loads/ (77.31%) >> 12,208,782 cpu_core/mem-stores/ (77.31%) >> 566,409,738 cpu_core/ref-cycles/ (84.87%) >> 23,118 cpu_core/cache-misses/ (76.71%) >> 7,212,602 cpu_core/cache-references/ (76.29%) >> >> 1.003228667 seconds time elapsed >> >> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> >> --- >> tools/perf/arch/x86/util/evsel.c | 21 +++++++++++++++++++-- >> 1 file changed, 19 insertions(+), 2 deletions(-) >> >> diff --git a/tools/perf/arch/x86/util/evsel.c b/tools/perf/arch/x86/util/evsel.c >> index 00cb4466b4ca..6eda5a491eda 100644 >> --- a/tools/perf/arch/x86/util/evsel.c >> +++ b/tools/perf/arch/x86/util/evsel.c >> @@ -31,10 +31,27 @@ void arch_evsel__fixup_new_cycles(struct perf_event_attr *attr) >> free(env.cpuid); >> } >> >> +static bool evsel__sys_has_perf_metrics(const struct evsel *evsel) >> +{ > > Why have this and not use topdown_sys_has_perf_metrics? It seems > strange to have the mix of evsel and PMU that this function is > testing.
This function tells whether the evsel's PMU supports perf metrics. The topdown_sys_has_perf_metrics() tells whether there is a PMU on the machine which supports perf metrics.
I don't think we want to group the topdown events on the cpu_atom. The evsel__sys_has_perf_metrics() can filter out the cpu_atom case.
I will add comments for the two functions to clarify. > >> + const char *pmu_name = evsel->pmu_name ? evsel->pmu_name : "cpu"; >> + >> + /* >> + * The PERF_TYPE_RAW type is the core PMU type. >> + * The slots event is only available for the core PMU, which >> + * supports the perf metrics feature. > > nit: Does "core PMU" mean /sys/devices/cpu_core ? It would be good to > disambiguate possibly by just using "cpu_core PMU".
No. The core PMU is to be distinguished with the uncore PMU. For a non-hybrid machine, the core PMU is the "cpu" PMU. For a hybrid machine, the core PMU is the "cpu_core" PMU.
I don't think we want to specify the "cpu_core" PMU here, because the function should work for both hybrid and non-hybrid platforms.
Thanks, Kan
> > Thanks, > Ian > > >> + * Checking both the PERF_TYPE_RAW type and the slots event >> + * should be good enough to detect the perf metrics feature. >> + */ >> + if ((evsel->core.attr.type == PERF_TYPE_RAW) && >> + pmu_have_event(pmu_name, "slots")) >> + return true; >> + >> + return false; >> +} >> + >> bool arch_evsel__must_be_in_group(const struct evsel *evsel) >> { >> - if ((evsel->pmu_name && strcmp(evsel->pmu_name, "cpu")) || >> - !pmu_have_event("cpu", "slots")) >> + if (!evsel__sys_has_perf_metrics(evsel)) >> return false; >> >> return evsel->name && >> -- >> 2.35.1 >>
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