[RFC/PATCH 17/38] perf tools: Maintain map groups list in a leader thread

[Namhyung Kim]

To support multi-threaded perf report, we need to maintain time-sorted
map groups.  Add ->mg_list member to struct thread and sort the list
by time.  Now leader threads have one more refcnt for map groups in
the list so also update the thread-mg-share test case.

Currently only add a new map groups when an exec (comm) event is
received.

Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/tests/thread-mg-share.c |   7 ++-
 tools/perf/util/event.c            |   2 +
 tools/perf/util/machine.c          |  15 ++++-
 tools/perf/util/map.c              |   3 +
 tools/perf/util/map.h              |   2 +
 tools/perf/util/thread.c           | 111 ++++++++++++++++++++++++++++++++++++-
 tools/perf/util/thread.h           |   3 +
 7 files changed, 138 insertions(+), 5 deletions(-)

diff --git a/tools/perf/tests/thread-mg-share.c b/tools/perf/tests/thread-mg-share.c
index 01fabb19d746..b258d5298b9b 100644
--- a/tools/perf/tests/thread-mg-share.c
+++ b/tools/perf/tests/thread-mg-share.c
@@ -23,6 +23,9 @@ int test__thread_mg_share(void)
 	 * with several threads and checks they properly share and
 	 * maintain map groups info (struct map_groups).
 	 *
+	 * Note that a leader thread has one more refcnt for its
+	 * (current) map groups.
+	 *
 	 * thread group (pid: 0, tids: 0, 1, 2, 3)
 	 * other  group (pid: 4, tids: 4, 5)
 	*/
@@ -43,7 +46,7 @@ int test__thread_mg_share(void)
 			leader && t1 && t2 && t3 && other);
 
 	mg = leader->mg;
-	TEST_ASSERT_EQUAL("wrong refcnt", atomic_read(&mg->refcnt), 4);
+	TEST_ASSERT_EQUAL("wrong refcnt", atomic_read(&mg->refcnt), 5);
 
 	/* test the map groups pointer is shared */
 	TEST_ASSERT_VAL("map groups don't match", mg == t1->mg);
@@ -71,7 +74,7 @@ int test__thread_mg_share(void)
 	machine__remove_thread(machine, other_leader);
 
 	other_mg = other->mg;
-	TEST_ASSERT_EQUAL("wrong refcnt", atomic_read(&other_mg->refcnt), 2);
+	TEST_ASSERT_EQUAL("wrong refcnt", atomic_read(&other_mg->refcnt), 3);
 
 	TEST_ASSERT_VAL("map groups don't match", other_mg == other_leader->mg);
 
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 3dff1b5cd4cc..887f18266ab5 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -914,6 +914,8 @@ void thread__find_addr_map(struct thread *thread, u8 cpumode,
 		return;
 	}
 
+	BUG_ON(mg == NULL);
+
 	if (cpumode == PERF_RECORD_MISC_KERNEL && perf_host) {
 		al->level = 'k';
 		mg = &machine->kmaps;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 7cfaa2c3f131..3373e8455945 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -349,8 +349,19 @@ static void machine__update_thread_pid(struct machine *machine,
 	if (!leader)
 		goto out_err;
 
-	if (!leader->mg)
-		leader->mg = map_groups__new(machine);
+	if (!leader->mg) {
+		struct map_groups *mg = map_groups__new(machine);
+
+		if (mg == NULL) {
+			pr_err("Not enough memory for map groups\n");
+			return;
+		}
+
+		if (thread__set_map_groups(leader, mg, 0) < 0) {
+			map_groups__put(mg);
+			goto out_err;
+		}
+	}
 
 	if (!leader->mg)
 		goto out_err;
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 4e38c396a897..addd4b323027 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -471,6 +471,8 @@ void map_groups__init(struct map_groups *mg, struct machine *machine)
 	}
 	mg->machine = machine;
 	atomic_set(&mg->refcnt, 1);
+	mg->timestamp = 0;
+	INIT_LIST_HEAD(&mg->list);
 }
 
 static void __maps__purge(struct maps *maps)
@@ -527,6 +529,7 @@ struct map_groups *map_groups__new(struct machine *machine)
 void map_groups__delete(struct map_groups *mg)
 {
 	map_groups__exit(mg);
+	list_del(&mg->list);
 	free(mg);
 }
 
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index 7309d64ce39e..1e3313a22d3a 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -68,6 +68,8 @@ struct map_groups {
 	struct maps	 maps[MAP__NR_TYPES];
 	struct machine	 *machine;
 	atomic_t	 refcnt;
+	u64		 timestamp;
+	struct list_head list;
 };
 
 struct map_groups *map_groups__new(struct machine *machine);
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index ad7c2a00bff8..33de8b010282 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -11,13 +11,79 @@
 #include "unwind.h"
 #include "machine.h"
 
+struct map_groups *thread__get_map_groups(struct thread *thread, u64 timestamp)
+{
+	struct map_groups *mg;
+	struct thread *leader = thread;
+
+	BUG_ON(thread->mg == NULL);
+
+	if (thread->tid != thread->pid_) {
+		leader = machine__find_thread_by_time(thread->mg->machine,
+						      thread->pid_, thread->pid_,
+						      timestamp);
+		if (leader == NULL)
+			goto out;
+	}
+
+	list_for_each_entry(mg, &leader->mg_list, list)
+		if (timestamp >= mg->timestamp)
+			return mg;
+
+out:
+	return thread->mg;
+}
+
+int thread__set_map_groups(struct thread *thread, struct map_groups *mg,
+			   u64 timestamp)
+{
+	struct list_head *pos;
+	struct map_groups *old;
+
+	if (mg == NULL)
+		return -ENOMEM;
+
+	/*
+	 * Only a leader thread can have map groups list - others
+	 * reference it through map_groups__get.  This means the
+	 * leader thread will have one more refcnt than others.
+	 */
+	if (thread->tid != thread->pid_)
+		return -EINVAL;
+
+	if (thread->mg) {
+		BUG_ON(atomic_read(&thread->mg->refcnt) <= 1);
+		map_groups__put(thread->mg);
+	}
+
+	/* sort by time */
+	list_for_each(pos, &thread->mg_list) {
+		old = list_entry(pos, struct map_groups, list);
+		if (timestamp > old->timestamp)
+			break;
+	}
+
+	list_add_tail(&mg->list, pos);
+	mg->timestamp = timestamp;
+
+	/* set current ->mg to most recent one */
+	thread->mg = list_first_entry(&thread->mg_list, struct map_groups, list);
+	/* increase one more refcnt for current */
+	map_groups__get(thread->mg);
+
+	return 0;
+}
+
 int thread__init_map_groups(struct thread *thread, struct machine *machine)
 {
 	struct thread *leader;
 	pid_t pid = thread->pid_;
 
 	if (pid == thread->tid || pid == -1) {
-		thread->mg = map_groups__new(machine);
+		struct map_groups *mg = map_groups__new(machine);
+
+		if (thread__set_map_groups(thread, mg, 0) < 0)
+			map_groups__put(mg);
 	} else {
 		leader = __machine__findnew_thread(machine, pid, pid);
 		if (leader)
@@ -39,6 +105,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
 		thread->ppid = -1;
 		thread->cpu = -1;
 		INIT_LIST_HEAD(&thread->comm_list);
+		INIT_LIST_HEAD(&thread->mg_list);
 
 		if (unwind__prepare_access(thread) < 0)
 			goto err_thread;
@@ -69,6 +136,7 @@ err_thread:
 void thread__delete(struct thread *thread)
 {
 	struct comm *comm, *tmp;
+	struct map_groups *mg, *tmp_mg;
 
 	BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));
 	BUG_ON(!list_empty(&thread->tid_list));
@@ -79,6 +147,10 @@ void thread__delete(struct thread *thread)
 		map_groups__put(thread->mg);
 		thread->mg = NULL;
 	}
+	/* only leader threads have mg list */
+	list_for_each_entry_safe(mg, tmp_mg, &thread->mg_list, list)
+		map_groups__put(mg);
+
 	list_for_each_entry_safe(comm, tmp, &thread->comm_list, list) {
 		list_del(&comm->list);
 		comm__free(comm);
@@ -152,6 +224,9 @@ struct comm *thread__comm_by_time(const struct thread *thread, u64 timestamp)
 	return list_last_entry(&thread->comm_list, struct comm, list);
 }
 
+static int thread__clone_map_groups(struct thread *thread,
+				    struct thread *parent);
+
 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
 		       bool exec)
 {
@@ -182,6 +257,40 @@ int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
 			unwind__flush_access(thread);
 	}
 
+	if (exec) {
+		struct machine *machine;
+
+		BUG_ON(thread->mg == NULL || thread->mg->machine == NULL);
+
+		machine = thread->mg->machine;
+
+		if (thread->tid != thread->pid_) {
+			struct map_groups *old = thread->mg;
+			struct thread *leader;
+
+			leader = machine__findnew_thread(machine, thread->pid_,
+							 thread->pid_);
+
+			/* now it'll be a new leader */
+			thread->pid_ = thread->tid;
+
+			thread->mg = map_groups__new(old->machine);
+			if (thread->mg == NULL)
+				return -ENOMEM;
+
+			/* save current mg in the new leader */
+			thread__clone_map_groups(thread, leader);
+
+			/* current mg of leader thread needs one more refcnt */
+			map_groups__get(thread->mg);
+
+			thread__set_map_groups(thread, thread->mg, old->timestamp);
+		}
+
+		/* create a new mg for newly executed binary */
+		thread__set_map_groups(thread, map_groups__new(machine), timestamp);
+	}
+
 	thread->comm_set = true;
 
 	return 0;
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 97026a9660ec..c8463d08a6dd 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -16,6 +16,7 @@ struct thread {
 	struct rb_node	 	rb_node;
 	struct list_head 	tid_list;
 	struct map_groups	*mg;
+	struct list_head	mg_list;
 	pid_t			pid_; /* Not all tools update this */
 	pid_t			tid;
 	pid_t			ppid;
@@ -71,6 +72,8 @@ struct comm *thread__exec_comm(const struct thread *thread);
 struct comm *thread__comm_by_time(const struct thread *thread, u64 timestamp);
 const char *thread__comm_str(const struct thread *thread);
 const char *thread__comm_str_by_time(const struct thread *thread, u64 timestamp);
+struct map_groups *thread__get_map_groups(struct thread *thread, u64 timestamp);
+int thread__set_map_groups(struct thread *thread, struct map_groups *mg, u64 timestamp);
 void thread__insert_map(struct thread *thread, struct map *map);
 int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp);
 size_t thread__fprintf(struct thread *thread, FILE *fp);
-- 
2.6.0

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