linux-kernel - [PATCH v2 1/2] perf pmu: Make pmu_alias

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Message-ID: <20251106233710.463949-1-irogers@google.com>
Date: Thu,  6 Nov 2025 15:37:09 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, James Clark <james.clark@...aro.org>, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: [PATCH v2 1/2] perf pmu: Make pmu_alias_terms weak again

The terms for a json event should be weak so they don't override
command line options.

Before:
```
$ perf record -vv -c 1000 -e uops_issued.any -o /dev/null true 2>&1
|grep "{ sample_period, sample_freq }"
 { sample_period, sample_freq }   200003
 { sample_period, sample_freq }   2000003
 { sample_period, sample_freq }   1000
```

After:
```
$ perf record -vv -c 1000 -e uops_issued.any -o /dev/null true 2>&1
|grep "{ sample_period, sample_freq }"
 { sample_period, sample_freq }   1000
 { sample_period, sample_freq }   1000
 { sample_period, sample_freq }   1000
```

Fixes: 84bae3af20d0 ("perf pmu: Don't eagerly parse event terms")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
v2: Expand the commit message with an example (Namhyung).
---
 tools/perf/util/pmu.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index d597263fab4f..f14f2a12d061 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -802,6 +802,7 @@ static int pmu_aliases_parse_eager(struct perf_pmu *pmu, int sysfs_fd)
 static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms)
 {
 	struct parse_events_terms alias_terms;
+	struct parse_events_term *term;
 	int ret;
 
 	parse_events_terms__init(&alias_terms);
@@ -812,6 +813,13 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms
 		parse_events_terms__exit(&alias_terms);
 		return ret;
 	}
+	list_for_each_entry(term, &alias_terms.terms, list) {
+		/*
+		 * Weak terms don't override command line options,
+		 * which we don't want for implicit terms in aliases.
+		 */
+		term->weak = true;
+	}
 	list_splice_init(&alias_terms.terms, terms);
 	parse_events_terms__exit(&alias_terms);
 	return 0;
-- 
2.51.2.1041.gc1ab5b90ca-goog