libperf cpumap: Grow array of read CPUs in smaller increments

Instead of growing the array by 2048, grow by the larger of the current
range or 16.

As ranges are typical for things like the online CPUs this will mean a
single allocation happens.

While uncore CPU maps will grow 16 at a time which is a value that is
generous except say on large servers.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ben Gainey <ben.gainey@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kyle Meyer <kyle.meyer@hpe.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241206044035.1062032-9-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 36f6579b3006348b7a7aa273883686f82106a607..fcc47214062aa462f5f85895d2347480acd45c88 100644 (file)
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -213,7 +213,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
                                        goto invalid;
 
                        if (nr_cpus == max_entries) {
-                               max_entries += MAX_NR_CPUS;
+                               max_entries += max(end_cpu - start_cpu + 1, 16UL);
                                tmp = realloc(tmp_cpus, max_entries * sizeof(struct perf_cpu));
                                if (tmp == NULL)
                                        goto invalid;
@@ -227,14 +227,15 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
                cpu_list = p;
        }
 
-       if (nr_cpus > 0)
+       if (nr_cpus > 0) {
                cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
-       else if (*cpu_list != '\0') {
+       } else if (*cpu_list != '\0') {
                pr_warning("Unexpected characters at end of cpu list ('%s'), using online CPUs.",
                           cpu_list);
                cpus = perf_cpu_map__new_online_cpus();
-       } else
+       } else {
                cpus = perf_cpu_map__new_any_cpu();
+       }
 invalid:
        free(tmp_cpus);
 out: