perf mem: Warn if memory events are not supported on all CPUs

It is possible that memory events are not supported on all CPUs.

Prints a warning by dumping the enabled CPU maps in this case.

Signed-off-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: John Garry <john.g.garry@oracle.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: coresight@lists.linaro.org
Link: https://lore.kernel.org/r/20240706152035.86983-3-leo.yan@arm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
index 429079329e48909f6bdea929da79593893cc8c88..be048bd02f36cc86ace9cb9d60bea62254748f94 100644 (file)
--- a/tools/perf/util/mem-events.c
+++ b/tools/perf/util/mem-events.c
@@ -8,6 +8,7 @@
 #include <unistd.h>
 #include <api/fs/fs.h>
 #include <linux/kernel.h>
+#include "cpumap.h"
 #include "map_symbol.h"
 #include "mem-events.h"
 #include "mem-info.h"
@@ -242,6 +243,7 @@ int perf_mem_events__record_args(const char **rec_argv, int *argv_nr)
        int i = *argv_nr;
        const char *s;
        char *copy;
+       struct perf_cpu_map *cpu_map = NULL;
 
        while ((pmu = perf_pmus__scan_mem(pmu)) != NULL) {
                for (int j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
@@ -266,7 +268,19 @@ int perf_mem_events__record_args(const char **rec_argv, int *argv_nr)
 
                        rec_argv[i++] = "-e";
                        rec_argv[i++] = copy;
+
+                       cpu_map = perf_cpu_map__merge(cpu_map, pmu->cpus);
+               }
+       }
+
+       if (cpu_map) {
+               if (!perf_cpu_map__equal(cpu_map, cpu_map__online())) {
+                       char buf[200];
+
+                       cpu_map__snprint(cpu_map, buf, sizeof(buf));
+                       pr_warning("Memory events are enabled on a subset of CPUs: %s\n", buf);
                }
+               perf_cpu_map__put(cpu_map);
        }
 
        *argv_nr = i;