Re: [PATCH 1/1] perf util: Do not reuse target->per_thread flag

From: Jin, Yao
Date: Mon Jan 22 2018 - 08:05:42 EST


Hi Mathieu,

Sorry, I just see this patch today.

I have tested this patch and it works.

Another idea from me is it doesn't need to add a new target->all_threads flag.

We just use target->per-thread && target->system_wide as a condition to check for all per-thread case.

I just think for your perf record case, the target->system_wide will not be set. Instead, if target->per-thread and target->system_wide are both set, that means we needs to trace on all threads, right?

Thanks
Jin Yao

On 1/13/2018 7:12 AM, Mathieu Poirier wrote:
Commit ("73c0ca1eee3d perf thread_map: Enumerate all threads from /proc")
is using the target->per_thread flag to specify that all threads in a
system should be taken into account. That is then used in function
thread_map__new_str() where all threads are added to evlist->threads.

Variable target->per_thread is also used by 'perf record' when handling
trace sessions using the --per-thread command line option. Since the
target->per_thread flag is set all threads will be added to
evlist->threads, which has the effect of creating a kernel event for each
thread in the system.

This patch address the issue by creating a new target->all_threads flag
that gets set from the 'stat' utility, avoiding any conflict with other
utilities using target->per_thread.

Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
---
tools/perf/builtin-stat.c | 2 +-
tools/perf/util/evlist.c | 2 +-
tools/perf/util/target.h | 1 +
tools/perf/util/thread_map.c | 4 ++--
tools/perf/util/thread_map.h | 2 +-
5 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 98bf9d32f222..87e156bfb45e 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -2831,7 +2831,7 @@ int cmd_stat(int argc, const char **argv)
target__validate(&target);
if ((stat_config.aggr_mode == AGGR_THREAD) && (target.system_wide))
- target.per_thread = true;
+ target.per_thread = target.all_threads = true;
if (perf_evlist__create_maps(evsel_list, &target) < 0) {
if (target__has_task(&target)) {
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index f0a5e09c4071..c239eb895612 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1106,7 +1106,7 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target)
struct thread_map *threads;
threads = thread_map__new_str(target->pid, target->tid, target->uid,
- target->per_thread);
+ target->all_threads);
if (!threads)
return -1;
diff --git a/tools/perf/util/target.h b/tools/perf/util/target.h
index 6ef01a83b24e..0da8ea2b6801 100644
--- a/tools/perf/util/target.h
+++ b/tools/perf/util/target.h
@@ -15,6 +15,7 @@ struct target {
bool uses_mmap;
bool default_per_cpu;
bool per_thread;
+ bool all_threads;
};
enum target_errno {
diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index 3e1038f6491c..729dad8f412d 100644
--- a/tools/perf/util/thread_map.c
+++ b/tools/perf/util/thread_map.c
@@ -323,7 +323,7 @@ struct thread_map *thread_map__new_by_tid_str(const char *tid_str)
}
struct thread_map *thread_map__new_str(const char *pid, const char *tid,
- uid_t uid, bool per_thread)
+ uid_t uid, bool all_threads)
{
if (pid)
return thread_map__new_by_pid_str(pid);
@@ -331,7 +331,7 @@ struct thread_map *thread_map__new_str(const char *pid, const char *tid,
if (!tid && uid != UINT_MAX)
return thread_map__new_by_uid(uid);
- if (per_thread)
+ if (all_threads)
return thread_map__new_all_cpus();
return thread_map__new_by_tid_str(tid);
diff --git a/tools/perf/util/thread_map.h b/tools/perf/util/thread_map.h
index 0a806b99e73c..5ec91cfd1869 100644
--- a/tools/perf/util/thread_map.h
+++ b/tools/perf/util/thread_map.h
@@ -31,7 +31,7 @@ struct thread_map *thread_map__get(struct thread_map *map);
void thread_map__put(struct thread_map *map);
struct thread_map *thread_map__new_str(const char *pid,
- const char *tid, uid_t uid, bool per_thread);
+ const char *tid, uid_t uid, bool all_threads);
struct thread_map *thread_map__new_by_tid_str(const char *tid_str);