[PATCH 06/23] perf mem: Check for memory events support

From: Jiri Olsa
Date: Mon Feb 15 2016 - 03:39:47 EST


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

$ perf mem record -e list
[ok] ldlat-loads
[ok] ldlat-stores

Link: http://lkml.kernel.org/n/tip-r8smhxjfe69q67jwt7mzs0e9@xxxxxxxxxxxxxx
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
tools/perf/builtin-mem.c | 14 +++++++++++++-
tools/perf/util/mem-events.c | 35 ++++++++++++++++++++++++++++++++---
tools/perf/util/mem-events.h | 3 +++
3 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-mem.c b/tools/perf/builtin-mem.c
index b3f8a89ede40..e64e0aa7ba0e 100644
--- a/tools/perf/builtin-mem.c
+++ b/tools/perf/builtin-mem.c
@@ -40,7 +40,8 @@ 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",
+ fprintf(stderr, "%s%-20s%s",
+ e->supported ? "[ok] " : " ",
e->tag, verbose ? "" : "\n");
if (verbose)
fprintf(stderr, " [%s]\n", e->name);
@@ -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 0b5247468462..b9a786346c03 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 {
@@ -18,6 +20,7 @@ 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 */

--
2.4.3