[v1,2/2] perf mem: Warn if memory events are not supported on all CPUs

Commit Message

Leo Yan June 23, 2024, 1:34 p.m. UTC

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 <[e-mail]>
---
 tools/perf/util/mem-events.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Patch

diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
index 6dda47bb774f..8aff2ca8bbd5 100644
--- 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;