[PATCH v2 4/6] perf cpumap: More cpu map reuse by merge.

[Ian Rogers]

perf_cpu_map__merge will reuse one of its arguments if they are equal or
the other argument is NULL. The arguments could be reused if it is known
one set of values is a subset of the other. For example, a map of 0-1
and a map of just 0 when merged yields the map of 0-1. Currently a new
map is created rather than adding a reference count to the original 0-1
map.

Signed-off-by: Ian Rogers <irogers at google.com>
---
 tools/lib/perf/cpumap.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index 23701024e0c0..384d5e076ee4 100644
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -355,17 +355,12 @@ struct perf_cpu_map *perf_cpu_map__merge(struct perf_cpu_map *orig,
 	int i, j, k;
 	struct perf_cpu_map *merged;
 
-	if (!orig && !other)
-		return NULL;
-	if (!orig) {
-		perf_cpu_map__get(other);
-		return other;
-	}
-	if (!other)
-		return orig;
-	if (orig->nr == other->nr &&
-	    !memcmp(orig->map, other->map, orig->nr * sizeof(struct perf_cpu)))
+	if (perf_cpu_map__is_subset(orig, other))
 		return orig;
+	if (perf_cpu_map__is_subset(other, orig)) {
+		perf_cpu_map__put(orig);
+		return perf_cpu_map__get(other);
+	}
 
 	tmp_len = orig->nr + other->nr;
 	tmp_cpus = malloc(tmp_len * sizeof(struct perf_cpu));
-- 
2.35.1.1021.g381101b075-goog