linux-kernel - [PATCH v2] perf stat: Fix non-uniquified hybrid legacy events

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Message-Id: <20250226145526.632380-1-james.clark@linaro.org>
Date: Wed, 26 Feb 2025 14:55:25 +0000
From: James Clark <james.clark@...aro.org>
To: linux-perf-users@...r.kernel.org,
	irogers@...gle.com,
	namhyung@...nel.org
Cc: James Clark <james.clark@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Yicong Yang <yangyicong@...ilicon.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] 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. Fix
it by checking if the evsel is hybrid and forcing needs_uniquify
before looking at the attr.type.

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")
Suggested-by: Ian Rogers <irogers@...gle.com>
Signed-off-by: James Clark <james.clark@...aro.org>
---

Changes since V1:
 * Move the existing evsel__is_hybrid() test earlier instead of looking
   at the PMU of the evsel. Looking at the PMU creates a dependency that
   the PMU is assigned which may prevent refactors in the future.

 tools/perf/util/stat-display.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index e65c7e9f15d1..e852ac0d9847 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -1688,6 +1688,12 @@ static void evsel__set_needs_uniquify(struct evsel *counter, const struct perf_s
 		return;
 	}
 
+	if (!config->hybrid_merge && evsel__is_hybrid(counter)) {
+		/* Unique hybrid counters necessary. */
+		counter->needs_uniquify = true;
+		return;
+	}
+
 	if  (counter->core.attr.type < PERF_TYPE_MAX && counter->core.attr.type != PERF_TYPE_RAW) {
 		/* Legacy event, don't uniquify. */
 		return;
@@ -1705,12 +1711,6 @@ static void evsel__set_needs_uniquify(struct evsel *counter, const struct perf_s
 		return;
 	}
 
-	if (!config->hybrid_merge && evsel__is_hybrid(counter)) {
-		/* Unique hybrid counters necessary. */
-		counter->needs_uniquify = true;
-		return;
-	}
-
 	/*
 	 * Do other non-merged events in the evlist have the same name? If so
 	 * uniquify is necessary.
-- 
2.34.1