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SubjectRe: [PATCH RFC V2 02/10] perf tools: using scandir to replace readdir
Em Sun, Sep 10, 2017 at 07:23:15PM -0700, kan.liang@intel.com escreveu:
> From: Kan Liang <kan.liang@intel.com>
>
> For perf_event__synthesize_threads, perf goes through all proc files
> serially by readdir.
> scandir did a snapshoot of proc, which is multithreading friendly.
>
> It's possible that some threads which are added during event synthesize.
> But the number of lost threads should be small.
> They should not impact the final analysis.

This one I had already merged into my perf/core branch,

- Arnaldo

> Signed-off-by: Kan Liang <kan.liang@intel.com>
> ---
> tools/perf/util/event.c | 46 ++++++++++++++++++++++++++--------------------
> 1 file changed, 26 insertions(+), 20 deletions(-)
>
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index 1c905ba..c31f678 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -683,12 +683,14 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
> bool mmap_data,
> unsigned int proc_map_timeout)
> {
> - DIR *proc;
> - char proc_path[PATH_MAX];
> - struct dirent *dirent;
> union perf_event *comm_event, *mmap_event, *fork_event;
> union perf_event *namespaces_event;
> + char proc_path[PATH_MAX];
> + struct dirent **dirent;
> int err = -1;
> + char *end;
> + pid_t pid;
> + int n, i;
>
> if (machine__is_default_guest(machine))
> return 0;
> @@ -712,29 +714,33 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
> goto out_free_fork;
>
> snprintf(proc_path, sizeof(proc_path), "%s/proc", machine->root_dir);
> - proc = opendir(proc_path);
> + n = scandir(proc_path, &dirent, 0, alphasort);
>
> - if (proc == NULL)
> + if (n < 0)
> goto out_free_namespaces;
>
> - while ((dirent = readdir(proc)) != NULL) {
> - char *end;
> - pid_t pid = strtol(dirent->d_name, &end, 10);
> -
> - if (*end) /* only interested in proper numerical dirents */
> + for (i = 0; i < n; i++) {
> + if (!isdigit(dirent[i]->d_name[0]))
> continue;
> - /*
> - * We may race with exiting thread, so don't stop just because
> - * one thread couldn't be synthesized.
> - */
> - __event__synthesize_thread(comm_event, mmap_event, fork_event,
> - namespaces_event, pid, 1, process,
> - tool, machine, mmap_data,
> - proc_map_timeout);
> - }
>
> + pid = (pid_t)strtol(dirent[i]->d_name, &end, 10);
> + /* only interested in proper numerical dirents */
> + if (!*end) {
> + /*
> + * We may race with exiting thread, so don't stop
> + * just because one thread couldn't be synthesized.
> + */
> + __event__synthesize_thread(comm_event, mmap_event,
> + fork_event, namespaces_event,
> + pid, 1, process, tool,
> + machine, mmap_data,
> + proc_map_timeout);
> + }
> + free(dirent[i]);
> + }
> + free(dirent);
> err = 0;
> - closedir(proc);
> +
> out_free_namespaces:
> free(namespaces_event);
> out_free_fork:
> --
> 2.5.5

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