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authorNamhyung Kim <namhyung@kernel.org>2020-12-16 18:05:56 +0900
committerArnaldo Carvalho de Melo <acme@redhat.com>2021-02-17 15:09:08 -0300
commit48859e5293a261437deb0231d78a388e242ed2d3 (patch)
treed9053042a5878714b76fd3c5ec68f9e8dcfc107a /tools/lib/api
parenttools api fs: Diet cgroupfs_find_mountpoint() (diff)
downloadlinux-dev-48859e5293a261437deb0231d78a388e242ed2d3.tar.xz
linux-dev-48859e5293a261437deb0231d78a388e242ed2d3.zip
tools api fs: Cache cgroupfs mount point
Currently it parses the /proc file everytime it opens a file in the cgroupfs. Save the last result to avoid it (assuming it won't be changed between the accesses). Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20201216090556.813996-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/lib/api')
-rw-r--r--tools/lib/api/fs/cgroup.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
index 262a4229e293..1573dae4259d 100644
--- a/tools/lib/api/fs/cgroup.c
+++ b/tools/lib/api/fs/cgroup.c
@@ -8,6 +8,14 @@
#include <string.h>
#include "fs.h"
+struct cgroupfs_cache_entry {
+ char subsys[32];
+ char mountpoint[PATH_MAX];
+};
+
+/* just cache last used one */
+static struct cgroupfs_cache_entry cached;
+
int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
{
FILE *fp;
@@ -16,6 +24,14 @@ int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
char *p, *path;
char mountpoint[PATH_MAX];
+ if (!strcmp(cached.subsys, subsys)) {
+ if (strlen(cached.mountpoint) < maxlen) {
+ strcpy(buf, cached.mountpoint);
+ return 0;
+ }
+ return -1;
+ }
+
fp = fopen("/proc/mounts", "r");
if (!fp)
return -1;
@@ -75,6 +91,9 @@ int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
free(line);
fclose(fp);
+ strncpy(cached.subsys, subsys, sizeof(cached.subsys) - 1);
+ strcpy(cached.mountpoint, mountpoint);
+
if (mountpoint[0] && strlen(mountpoint) < maxlen) {
strcpy(buf, mountpoint);
return 0;