Re: [PATCH v5 10/12] perf util: Reuse thread_map__new_by_uid to enumerate threads from /proc

From: Jin, Yao
Date: Fri Dec 01 2017 - 23:53:26 EST



On 12/1/2017 11:02 PM, Arnaldo Carvalho de Melo wrote:
Em Fri, Dec 01, 2017 at 11:44:25AM -0300, Arnaldo Carvalho de Melo escreveu:
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.jin@xxxxxxxxxxxxxxx>
---
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:


The one below even compiles, I'll push what I merged already and we can
continue from there:

[acme@jouet linux]$ git log --oneline -3
5cc4fc8994eb (HEAD -> perf/core) perf thread_map: Add method to map all threads in the system
9e49c22bd4d8 perf stat: Add rbtree node_delete op
1c92e3226546 perf rblist: Create rblist__exit() function
[acme@jouet linux]$



Yes we can continue from these commits.

I just pull the branch perf/core from https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git, but it looks the new commits have not been synced.

Maybe I will wait to next week to see if the new commits are synced and then continue the work.

Thanks
Jin Yao

commit 5cc4fc8994eb3f3af1950f3b726b6008900c7b06
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Date: Fri Dec 1 11:44:30 2017 -0300

perf thread_map: Add method to map all threads in the system
Reusing the thread_map__new_by_uid() proc scanning already in place to
return a map with all threads in the system.
Based-on-a-patch-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/n/tip-khh28q0wwqbqtrk32bfe07hd@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index be0d5a736dea..2b653853eec2 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 != UINT_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_map__new_all_cpus(UINT_MAX);
+}
+
+struct thread_map *thread_map__new_by_uid(uid_t uid)
+{
+ return __thread_map__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);