Em Wed, Dec 16, 2020 at 06:05:56PM +0900, Namhyung Kim escreveu:
> 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).
Which is the most likely case, but can't we use something like inotify
to detect that and bail out or warn the user?
- Arnaldo
> Signed-off-by: Namhyung Kim <namhy...@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
>
--
- Arnaldo
