Mathieu Poirier reports issue in commit ("73c0ca1eee3d perf thread_map:
Enumerate all threads from /proc") that it has negative impact on
'perf record --per-thread'. It has the effect of creating a kernel event
for each thread in the system for 'perf record --per-thread'.
Mathieu Poirier's patch ("perf util: Do not reuse target->per_thread flag")
can fix this issue by creating a new target->all_threads flag.
This patch is based on Mathieu Poirier's patch but it doesn't use a new
target->all_threads flag. This patch just uses 'target->per_thread &&
target->system_wide' as a condition to check for all threads case.
v2:
---
According to Jiri's comment, add description to explain why the patch
uses 'target->per_thread && target->system_wide'.
v2 doesn't have functional change.
Signed-off-by: Jin Yao <yao....@linux.intel.com>
---
tools/perf/util/evlist.c | 20 +++++++++++++++++++-
tools/perf/util/thread_map.c | 4 ++--
tools/perf/util/thread_map.h | 2 +-
3 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index ac35cd2..3eea0f8 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1106,8 +1106,26 @@ int perf_evlist__create_maps(struct perf_evlist *evlist,
struct target *target)
struct cpu_map *cpus;
struct thread_map *threads;
+ /*
+ * If specify '-a' and '--per-thread' to perf record, perf record
+ * will override '--per-thread'. target->per_thread = false and
+ * target->system_wide = true.
+ *
+ * If specify '--per-thread' only to perf record,
+ * target->per_thread = true and target->system_wide = false.
+ *
+ * So target->per_thread && target->system_wide is false.
+ * For perf record, thread_map__new_str doesn't call
+ * thread_map__new_all_cpus. That will keep perf record's
+ * current behavior.
+ *
+ * For perf stat, it allows the case that target->per_thread and
+ * target->system_wide are all true. It means to collect system-wide
+ * per-thread data. thread_map__new_str will call
+ * thread_map__new_all_cpus to enumerate all threads.
+ */
threads = thread_map__new_str(target->pid, target->tid, target->uid,
- target->per_thread);
+ target->per_thread &&
target->system_wide);
if (!threads)
return -1;
diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index 3e1038f..729dad8 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 0a806b9..5ec91cf 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);
--
2.7.4
