perf cpumap: More cpu map reuse by merge.

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@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Antonov <alexander.antonov@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: German Gomez <german.gomez@arm.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: John Garry <john.garry@huawei.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20220328232648.2127340-5-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index 2370102..384d5e0 100644 (file)
--- 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));