linux-kernel - [PATCH] perf stat: Fix non-uniquified hybrid legacy events

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Message-Id: <20250212122413.1184503-1-james.clark@linaro.org>
Date: Wed, 12 Feb 2025 12:24:12 +0000
From: James Clark <james.clark@...aro.org>
To: linux-perf-users@...r.kernel.org
Cc: Robin.Murphy@....com,
	James Clark <james.clark@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] perf stat: Fix non-uniquified hybrid legacy events

Legacy hybrid events have attr.type == PERF_TYPE_HARDWARE, so they look
like plain legacy events if we only look at attr.type. But legacy events
should still be uniquified if they were opened on a non-legacy PMU.
Previously we looked at the PMU type to determine legacy vs hybrid
events here so revert this particular check to how it was before the
linked fixes commit.

counter->pmu doesn't need to be null checked twice, in fact it is
required for any kind of uniquification so make that a separate check.

This restores PMU names on hybrid systems and also changes "perf stat
metrics (shadow stat) test" from a FAIL back to a SKIP (on hybrid). The
test was gated on "cycles" appearing alone which doesn't happen on
here.

Before:

  $ perf stat -- true
  ...
     <not counted>      instructions:u                           (0.00%)
           162,536      instructions:u            # 0.58  insn per cycle
  ...

After:

 $ perf stat -- true
 ...
     <not counted>      cpu_atom/instructions/u                  (0.00%)
           162,541      cpu_core/instructions/u   # 0.62  insn per cycle
 ...

Fixes: 357b965deba9 ("perf stat: Changes to event name uniquification")
Signed-off-by: James Clark <james.clark@...aro.org>
---
 tools/perf/util/stat-display.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index e65c7e9f15d1..eae34ba95f59 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -1688,12 +1688,17 @@ static void evsel__set_needs_uniquify(struct evsel *counter, const struct perf_s
 		return;
 	}
 
-	if  (counter->core.attr.type < PERF_TYPE_MAX && counter->core.attr.type != PERF_TYPE_RAW) {
+	if (!counter->pmu) {
+		/* evsel__uniquify_counter() uses counter->pmu for the name */
+		return;
+	}
+
+	if (counter->pmu->type < PERF_TYPE_MAX && counter->pmu->type != PERF_TYPE_RAW) {
 		/* Legacy event, don't uniquify. */
 		return;
 	}
 
-	if (counter->pmu && counter->pmu->is_core &&
+	if (counter->pmu->is_core &&
 	    counter->alternate_hw_config != PERF_COUNT_HW_MAX) {
 		/* A sysfs or json event replacing a legacy event, don't uniquify. */
 		return;
-- 
2.34.1