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perf pmu: Don't double count common sysfs and json events

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After pmu_add_cpu_aliases() is called, perf_pmu__num_events() returns an
incorrect value that double counts common events and doesn't match the
actual count of events in the alias list. This is because after
'cpu_aliases_added == true', the number of events returned is
'sysfs_aliases + cpu_json_aliases'. But when adding 'case
EVENT_SRC_SYSFS' events, 'sysfs_aliases' and 'cpu_json_aliases' are both
incremented together, failing to account that these ones overlap and
only add a single item to the list. Fix it by adding another counter for
overlapping events which doesn't influence 'cpu_json_aliases'.

There doesn't seem to be a current issue because it's used in perf list
before pmu_add_cpu_aliases() so the correct value is returned. Other
uses in tests may also miss it for other reasons like only looking at
uncore events. However it's marked as a fixes commit in case any new fix
with new uses of perf_pmu__num_events() is backported.

Fixes: d9c5f5f94c2d ("perf pmu: Count sys and cpuid JSON events separately")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250226104111.564443-3-james.clark@linaro.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
James Clark 2025-02-26 10:41:01 +00:00 committed by Namhyung Kim
parent 72c6f57a41
commit c9d699e10f
2 changed files with 9 additions and 3 deletions
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7
tools/perf/util/pmu.c
View File

@ -595,7 +595,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
};
if (pmu_events_table__find_event(pmu->events_table, pmu, name,
update_alias, &data) == 0)
pmu->cpu_json_aliases++;
pmu->cpu_common_json_aliases++;
}
pmu->sysfs_aliases++;
break;
@ -1880,9 +1880,10 @@ size_t perf_pmu__num_events(struct perf_pmu *pmu)
if (pmu->cpu_aliases_added)
nr += pmu->cpu_json_aliases;
else if (pmu->events_table)
nr += pmu_events_table__num_events(pmu->events_table, pmu) - pmu->cpu_json_aliases;
nr += pmu_events_table__num_events(pmu->events_table, pmu) -
pmu->cpu_common_json_aliases;
else
assert(pmu->cpu_json_aliases == 0);
assert(pmu->cpu_json_aliases == 0 && pmu->cpu_common_json_aliases == 0);
if (perf_pmu__is_tool(pmu))
nr -= tool_pmu__num_skip_events();

5
tools/perf/util/pmu.h
View File

@ -136,6 +136,11 @@ struct perf_pmu {
uint32_t cpu_json_aliases;
/** @sys_json_aliases: Number of json event aliases loaded matching the PMU's identifier. */
uint32_t sys_json_aliases;
/**
* @cpu_common_json_aliases: Number of json events that overlapped with sysfs when
* loading all sysfs events.
*/
uint32_t cpu_common_json_aliases;
/** @sysfs_aliases_loaded: Are sysfs aliases loaded from disk? */
bool sysfs_aliases_loaded;
/**