linux-kernel - [PATCH 2/5] libperf: Propagate maps only if necessary

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Date:   Fri, 30 Sep 2022 10:27:11 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Leo Yan <leo.yan@...aro.org>
Subject: [PATCH 2/5] libperf: Propagate maps only if necessary

The current code propagate evsel's cpu map settings to evlist when it's
added to an evlist.  But the evlist->all_cpus and each evsel's cpus will
be updated in perf_evlist__set_maps() later.  No need to do it before
evlist's cpus are set actually.

In fact it discards this intermediate all_cpus maps at the beginning
of perf_evlist__set_maps().  Let's not do this.  It's only needed when
an evsel is added after the evlist cpu/thread maps are set.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/lib/perf/evlist.c                  | 8 ++++----
 tools/lib/perf/include/internal/evlist.h | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index 187129652ab6..c5f65b89d77a 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -67,9 +67,7 @@ static void perf_evlist__propagate_maps(struct perf_evlist *evlist)
 {
 	struct perf_evsel *evsel;
 
-	/* Recomputing all_cpus, so start with a blank slate. */
-	perf_cpu_map__put(evlist->all_cpus);
-	evlist->all_cpus = NULL;
+	evlist->needs_map_propagation = true;
 
 	perf_evlist__for_each_evsel(evlist, evsel)
 		__perf_evlist__propagate_maps(evlist, evsel);
@@ -81,7 +79,9 @@ void perf_evlist__add(struct perf_evlist *evlist,
 	evsel->idx = evlist->nr_entries;
 	list_add_tail(&evsel->node, &evlist->entries);
 	evlist->nr_entries += 1;
-	__perf_evlist__propagate_maps(evlist, evsel);
+
+	if (evlist->needs_map_propagation)
+		__perf_evlist__propagate_maps(evlist, evsel);
 }
 
 void perf_evlist__remove(struct perf_evlist *evlist,
diff --git a/tools/lib/perf/include/internal/evlist.h b/tools/lib/perf/include/internal/evlist.h
index 6f89aec3e608..850f07070036 100644
--- a/tools/lib/perf/include/internal/evlist.h
+++ b/tools/lib/perf/include/internal/evlist.h
@@ -19,6 +19,7 @@ struct perf_evlist {
 	int			 nr_entries;
 	int			 nr_groups;
 	bool			 has_user_cpus;
+	bool			 needs_map_propagation;
 	/**
 	 * The cpus passed from the command line or all online CPUs by
 	 * default.
-- 
2.38.0.rc1.362.ged0d419d3c-goog