[PATCH 01/31] perf mem record: Check for memory events support

From: Arnaldo Carvalho de Melo
Date: Wed Feb 24 2016 - 21:04:03 EST


From: Jiri Olsa <jolsa@xxxxxxxxxx>

Check if current kernel support available memory events and display the
status within -e list option:

$ perf mem record -e list
ldlat-loads : available
ldlat-stores : available

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1456303616-26926-2-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-mem.c | 20 ++++++++++++++++----
tools/perf/util/mem-events.c | 35 ++++++++++++++++++++++++++++++++---
tools/perf/util/mem-events.h | 3 +++
3 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/tools/perf/builtin-mem.c b/tools/perf/builtin-mem.c
index b3f8a89ede40..f1fa7b8d1f69 100644
--- a/tools/perf/builtin-mem.c
+++ b/tools/perf/builtin-mem.c
@@ -40,10 +40,11 @@ static int parse_record_events(const struct option *opt,
for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
struct perf_mem_event *e = &perf_mem_events[j];

- fprintf(stderr, "%-20s%s",
- e->tag, verbose ? "" : "\n");
- if (verbose)
- fprintf(stderr, " [%s]\n", e->name);
+ fprintf(stderr, "%-13s%-*s%s\n",
+ e->tag,
+ verbose ? 25 : 0,
+ verbose ? e->name : "",
+ e->supported ? ": available" : "");
}
exit(0);
}
@@ -92,6 +93,12 @@ static int __cmd_record(int argc, const char **argv, struct perf_mem *mem)
if (!perf_mem_events[j].record)
continue;

+ if (!perf_mem_events[j].supported) {
+ pr_err("failed: event '%s' not supported\n",
+ perf_mem_events[j].name);
+ return -1;
+ }
+
rec_argv[i++] = "-e";
rec_argv[i++] = perf_mem_events[j].name;
};
@@ -355,6 +362,11 @@ int cmd_mem(int argc, const char **argv, const char *prefix __maybe_unused)
NULL
};

+ if (perf_mem_events__init()) {
+ pr_err("failed: memory events not supported\n");
+ return -1;
+ }
+
argc = parse_options_subcommand(argc, argv, mem_options, mem_subcommands,
mem_usage, PARSE_OPT_STOP_AT_NON_OPTION);

diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
index b1507c04b257..e21853fe1312 100644
--- a/tools/perf/util/mem-events.c
+++ b/tools/perf/util/mem-events.c
@@ -2,15 +2,20 @@
#include <stdlib.h>
#include <string.h>
#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <api/fs/fs.h>
#include "mem-events.h"
#include "debug.h"

-#define E(t, n) { .tag = t, .name = n }
+#define E(t, n, s) { .tag = t, .name = n, .sysfs_name = s }

struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX] = {
- E("ldlat-loads", "cpu/mem-loads,ldlat=30/P"),
- E("ldlat-stores", "cpu/mem-stores/P"),
+ E("ldlat-loads", "cpu/mem-loads,ldlat=30/P", "mem-loads"),
+ E("ldlat-stores", "cpu/mem-stores/P", "mem-stores"),
};
+#undef E

#undef E

@@ -49,3 +54,27 @@ int perf_mem_events__parse(const char *str)
pr_err("failed: event '%s' not found, use '-e list' to get list of available events\n", str);
return -1;
}
+
+int perf_mem_events__init(void)
+{
+ const char *mnt = sysfs__mount();
+ bool found = false;
+ int j;
+
+ if (!mnt)
+ return -ENOENT;
+
+ for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
+ char path[PATH_MAX];
+ struct perf_mem_event *e = &perf_mem_events[j];
+ struct stat st;
+
+ scnprintf(path, PATH_MAX, "%s/devices/cpu/events/%s",
+ mnt, e->sysfs_name);
+
+ if (!stat(path, &st))
+ e->supported = found = true;
+ }
+
+ return found ? 0 : -ENOENT;
+}
diff --git a/tools/perf/util/mem-events.h b/tools/perf/util/mem-events.h
index 2995bae6ac33..75c1660bda62 100644
--- a/tools/perf/util/mem-events.h
+++ b/tools/perf/util/mem-events.h
@@ -5,8 +5,10 @@

struct perf_mem_event {
bool record;
+ bool supported;
const char *tag;
const char *name;
+ const char *sysfs_name;
};

enum {
@@ -18,5 +20,6 @@ enum {
extern struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX];

int perf_mem_events__parse(const char *str);
+int perf_mem_events__init(void);

#endif /* __PERF_MEM_EVENTS_H */
--
2.5.0