[PATCH 6.6 370/638] perf pmu: Treat the msr pmu as software

Sasha Levin
2024-03-24T23:07:20Z

From: Ian Rogers <irogers@google.com>

[ Upstream commit 24852ef2e2d5c555c2da05baff112ea414b6e0f5 ]

The msr PMU is a software one, meaning msr events may be grouped
with events in a hardware context. As the msr PMU isn't marked as a
software PMU by perf_pmu__is_software, groups with the msr PMU in
are broken and the msr events placed in a different group. This
may lead to multiplexing errors where a hardware event isn't
counted while the msr event, such as tsc, is. Fix all of this by
marking the msr PMU as software, which agrees with the driver.

Before:
```
$ perf stat -e '{slots,tsc}' -a true
WARNING: events were regrouped to match PMUs

Performance counter stats for 'system wide':

1,750,335 slots
4,243,557 tsc

0.001456717 seconds time elapsed
```

After:
```
$ perf stat -e '{slots,tsc}' -a true
Performance counter stats for 'system wide':

12,526,380 slots
3,415,163 tsc

0.001488360 seconds time elapsed
```

Fixes: 251aa040244a ("perf parse-events: Wildcard most "numeric" events")
Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Cc: James Clark <james.clark@arm.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Edward Baker <edward.baker@intel.com>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Samantha Alt <samantha.alt@intel.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Link: https://lore.kernel.org/r/20240124234200.1510417-1-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/pmu.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index d515ba8a0e160..a3c7814116c7c 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1735,6 +1735,12 @@ bool pmu__name_match(const struct perf_pmu *pmu, const char *pmu_name)

bool perf_pmu__is_software(const struct perf_pmu *pmu)
{
+ const char *known_sw_pmus[] = {
+ "kprobe",
+ "msr",
+ "uprobe",
+ };
+
if (pmu->is_core || pmu->is_uncore || pmu->auxtrace)
return false;
switch (pmu->type) {
@@ -1746,7 +1752,11 @@ bool perf_pmu__is_software(const struct perf_pmu *pmu)
case PERF_TYPE_BREAKPOINT: return true;
default: break;
}
- return !strcmp(pmu->name, "kprobe") || !strcmp(pmu->name, "uprobe");
+ for (size_t i = 0; i < ARRAY_SIZE(known_sw_pmus); i++) {
+ if (!strcmp(pmu->name, known_sw_pmus[i]))
+ return true;
+ }
+ return false;
}

FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name)
--
2.43.0