From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>, Jiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Stephane Eranian <eranian@google.com>,
Ian Rogers <irogers@google.com>, Andi Kleen <ak@linux.intel.com>
Subject: [PATCH 3/3] tools/lib/fs: Cache cgroupfs mount point
Date: Wed, 16 Dec 2020 18:05:56 +0900 [thread overview]
Message-ID: <20201216090556.813996-3-namhyung@kernel.org> (raw)
In-Reply-To: <20201216090556.813996-1-namhyung@kernel.org>
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>
---
tools/lib/api/fs/cgroup.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
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;
--
2.29.2.684.gfbc64c5ab5-goog
next prev parent reply other threads:[~2020-12-16 9:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 9:05 [PATCH 1/3] tools/lib/fs: Prefer cgroup v1 path Namhyung Kim
2020-12-16 9:05 ` [PATCH 2/3] tools/lib/fs: Diet cgroupfs_find_mountpoint() Namhyung Kim
2020-12-28 8:31 ` Jiri Olsa
2020-12-29 5:27 ` Namhyung Kim
2020-12-29 9:39 ` Jiri Olsa
2020-12-16 9:05 ` Namhyung Kim [this message]
2020-12-29 11:51 ` [PATCH 3/3] tools/lib/fs: Cache cgroupfs mount point Arnaldo Carvalho de Melo
2021-01-06 1:33 ` Namhyung Kim
2021-01-08 5:51 ` Namhyung Kim
2021-01-21 4:33 ` Namhyung Kim
2021-02-17 12:58 ` Arnaldo Carvalho de Melo
2021-02-19 10:05 ` Namhyung Kim
2021-02-19 11:37 ` Arnaldo Carvalho de Melo
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