On 12/1/2017 10:44 PM, Arnaldo Carvalho de Melo wrote:
Em Fri, Dec 01, 2017 at 06:57:34PM +0800, Jin Yao escreveu:
Perf already has a function thread_map__new_by_uid() which can
enumerate all threads from /proc by uid.

This patch creates a static function enumerate_threads() which
reuses the common code in thread_map__new_by_uid() to enumerate
threads from /proc.

The enumerate_threads() is shared by thread_map__new_by_uid()
and a new function thread_map__new_threads().

The new function thread_map__new_threads() is called to enumerate
all threads from /proc.

Signed-off-by: Jin Yao <yao....@linux.intel.com>
---
  tools/perf/tests/thread-map.c |  2 +-
  tools/perf/util/evlist.c      |  3 ++-
  tools/perf/util/thread_map.c  | 19 ++++++++++++++++---
  tools/perf/util/thread_map.h  |  3 ++-
  4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/tools/perf/tests/thread-map.c b/tools/perf/tests/thread-map.c
index dbcb6a1..4de1939 100644
--- a/tools/perf/tests/thread-map.c
+++ b/tools/perf/tests/thread-map.c
@@ -105,7 +105,7 @@ int test__thread_map_remove(struct test *test 
__maybe_unused, int subtest __mayb
        TEST_ASSERT_VAL("failed to allocate map string",
                        asprintf(&str, "%d,%d", getpid(), getppid()) >= 0);
- threads = thread_map__new_str(str, NULL, 0);
+       threads = thread_map__new_str(str, NULL, 0, false);
TEST_ASSERT_VAL("failed to allocate thread_map",
                        threads);
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 199bb82..05b8f2b 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1102,7 +1102,8 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, 
struct target *target)
        struct cpu_map *cpus;
        struct thread_map *threads;
- threads = thread_map__new_str(target->pid, target->tid, target->uid);
+       threads = thread_map__new_str(target->pid, target->tid, target->uid,
+                                     target->per_thread);
if (!threads)
                return -1;
diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index be0d5a7..5672268 100644
--- a/tools/perf/util/thread_map.c
+++ b/tools/perf/util/thread_map.c
@@ -92,7 +92,7 @@ struct thread_map *thread_map__new_by_tid(pid_t tid)
        return threads;
  }
-struct thread_map *thread_map__new_by_uid(uid_t uid)
+static struct thread_map *enumerate_threads(uid_t uid)
  {
        DIR *proc;
        int max_threads = 32, items, i;
@@ -124,7 +124,7 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
                if (stat(path, &st) != 0)
                        continue;

Look, for the case where you want all threads enumerated you will incur
the above stat() cost for all of them and will not use it at all...

And new_threads() seems vague, I'm using the ter used by 'perf record'
for system wide sampling, see the patch below:

diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index be0d5a736dea..79d11bd4543a 100644
--- a/tools/perf/util/thread_map.c
+++ b/tools/perf/util/thread_map.c
@@ -92,7 +92,7 @@ struct thread_map *thread_map__new_by_tid(pid_t tid)
        return threads;
  }
-struct thread_map *thread_map__new_by_uid(uid_t uid)
+static struct thread_map *__thread_map__new_all_cpus(uid_t uid)
  {
        DIR *proc;
        int max_threads = 32, items, i;
@@ -113,7 +113,6 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
        while ((dirent = readdir(proc)) != NULL) {
                char *end;
                bool grow = false;
-               struct stat st;
                pid_t pid = strtol(dirent->d_name, &end, 10);
if (*end) /* only interested in proper numerical dirents */
@@ -121,11 +120,12 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
snprintf(path, sizeof(path), "/proc/%s", dirent->d_name); - if (stat(path, &st) != 0)
-                       continue;
+               if (uid != UID_MAX) {
+                       struct stat st;
- if (st.st_uid != uid)
-                       continue;
+                       if (stat(path, &st) != 0 || st.st_uid != uid)
+                               continue;
+               }
snprintf(path, sizeof(path), "/proc/%d/task", pid);
                items = scandir(path, &namelist, filter, NULL);
@@ -178,6 +178,16 @@ struct thread_map *thread_map__new_by_uid(uid_t uid)
        goto out_closedir;
  }
+struct thread_map *thread_map__new_all_cpus(void)
+{
+       return __thread__new_all_cpus(UID_MAX);
+}
+
+struct thread_map *thread_map__new_by_uid(uid_t uid)
+{
+       return __thread__new_all_cpus(uid);
+}
+
  struct thread_map *thread_map__new(pid_t pid, pid_t tid, uid_t uid)
  {
        if (pid != -1)
diff --git a/tools/perf/util/thread_map.h b/tools/perf/util/thread_map.h
index f15803985435..07a765fb22bb 100644
--- a/tools/perf/util/thread_map.h
+++ b/tools/perf/util/thread_map.h
@@ -23,6 +23,7 @@ struct thread_map *thread_map__new_dummy(void);
  struct thread_map *thread_map__new_by_pid(pid_t pid);
  struct thread_map *thread_map__new_by_tid(pid_t tid);
  struct thread_map *thread_map__new_by_uid(uid_t uid);
+struct thread_map *thread_map__new_all_cpus(void);
  struct thread_map *thread_map__new(pid_t pid, pid_t tid, uid_t uid);
  struct thread_map *thread_map__new_event(struct thread_map_event *event);

It looks good, thanks Arnaldo!

Thanks
Jin Yao

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