perf tools: Provide mutex wrappers for pthreads rwlocks

Andi reported a performance drop in single threaded perf tools such as
'perf script' due to the growing number of locks being put in place to
allow for multithreaded tools, so wrap the POSIX threads rwlock routines
with the names used for such kinds of locks in the Linux kernel and then
allow for tools to ask for those locks to be used or not.

I.e. a tool may have a multithreaded phase and then switch to single
threaded, like the upcoming patches for the synthesizing of
PERF_RECORD_{FORK,MMAP,etc} for pre-existing processes to then switch to
single threaded mode in 'perf top'.

The init routines will not be conditional, this way starting as single
threaded to then move to multi threaded mode should be possible.

Reported-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170404161739.GH12903@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 21 insertions, 20 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index ddeea05eae86..585b4a3d64a4 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -30,7 +30,7 @@ static void dsos__init(struct dsos *dsos)
 {
 	INIT_LIST_HEAD(&dsos->head);
 	dsos->root = RB_ROOT;
-	pthread_rwlock_init(&dsos->lock, NULL);
+	init_rwsem(&dsos->lock);
 }
 
 static void machine__threads_init(struct machine *machine)
@@ -40,7 +40,7 @@ static void machine__threads_init(struct machine *machine)
 	for (i = 0; i < THREADS__TABLE_SIZE; i++) {
 		struct threads *threads = &machine->threads[i];
 		threads->entries = RB_ROOT;
-		pthread_rwlock_init(&threads->lock, NULL);
+		init_rwsem(&threads->lock);
 		threads->nr = 0;
 		INIT_LIST_HEAD(&threads->dead);
 		threads->last_match = NULL;
@@ -130,7 +130,7 @@ static void dsos__purge(struct dsos *dsos)
 {
 	struct dso *pos, *n;
 
-	pthread_rwlock_wrlock(&dsos->lock);
+	down_write(&dsos->lock);
 
 	list_for_each_entry_safe(pos, n, &dsos->head, node) {
 		RB_CLEAR_NODE(&pos->rb_node);
@@ -139,13 +139,13 @@ static void dsos__purge(struct dsos *dsos)
 		dso__put(pos);
 	}
 
-	pthread_rwlock_unlock(&dsos->lock);
+	up_write(&dsos->lock);
 }
 
 static void dsos__exit(struct dsos *dsos)
 {
 	dsos__purge(dsos);
-	pthread_rwlock_destroy(&dsos->lock);
+	exit_rwsem(&dsos->lock);
 }
 
 void machine__delete_threads(struct machine *machine)
@@ -155,7 +155,7 @@ void machine__delete_threads(struct machine *machine)
 
 	for (i = 0; i < THREADS__TABLE_SIZE; i++) {
 		struct threads *threads = &machine->threads[i];
-		pthread_rwlock_wrlock(&threads->lock);
+		down_write(&threads->lock);
 		nd = rb_first(&threads->entries);
 		while (nd) {
 			struct thread *t = rb_entry(nd, struct thread, rb_node);
@@ -163,7 +163,7 @@ void machine__delete_threads(struct machine *machine)
 			nd = rb_next(nd);
 			__machine__remove_thread(machine, t, false);
 		}
-		pthread_rwlock_unlock(&threads->lock);
+		up_write(&threads->lock);
 	}
 }
 
@@ -180,7 +180,7 @@ void machine__exit(struct machine *machine)
 
 	for (i = 0; i < THREADS__TABLE_SIZE; i++) {
 		struct threads *threads = &machine->threads[i];
-		pthread_rwlock_destroy(&threads->lock);
+		exit_rwsem(&threads->lock);
 	}
 }
 
@@ -482,9 +482,9 @@ struct thread *machine__findnew_thread(struct machine *machine, pid_t pid,
 	struct threads *threads = machine__threads(machine, tid);
 	struct thread *th;
 
-	pthread_rwlock_wrlock(&threads->lock);
+	down_write(&threads->lock);
 	th = __machine__findnew_thread(machine, pid, tid);
-	pthread_rwlock_unlock(&threads->lock);
+	up_write(&threads->lock);
 	return th;
 }
 
@@ -494,9 +494,9 @@ struct thread *machine__find_thread(struct machine *machine, pid_t pid,
 	struct threads *threads = machine__threads(machine, tid);
 	struct thread *th;
 
-	pthread_rwlock_rdlock(&threads->lock);
+	down_read(&threads->lock);
 	th =  ____machine__findnew_thread(machine, threads, pid, tid, false);
-	pthread_rwlock_unlock(&threads->lock);
+	up_read(&threads->lock);
 	return th;
 }
 
@@ -588,7 +588,7 @@ static struct dso *machine__findnew_module_dso(struct machine *machine,
 {
 	struct dso *dso;
 
-	pthread_rwlock_wrlock(&machine->dsos.lock);
+	down_write(&machine->dsos.lock);
 
 	dso = __dsos__find(&machine->dsos, m->name, true);
 	if (!dso) {
@@ -602,7 +602,7 @@ static struct dso *machine__findnew_module_dso(struct machine *machine,
 
 	dso__get(dso);
 out_unlock:
-	pthread_rwlock_unlock(&machine->dsos.lock);
+	up_write(&machine->dsos.lock);
 	return dso;
 }
 
@@ -749,7 +749,8 @@ size_t machine__fprintf(struct machine *machine, FILE *fp)
 
 	for (i = 0; i < THREADS__TABLE_SIZE; i++) {
 		struct threads *threads = &machine->threads[i];
-		pthread_rwlock_rdlock(&threads->lock);
+
+		down_read(&threads->lock);
 
 		ret = fprintf(fp, "Threads: %u\n", threads->nr);
 
@@ -759,7 +760,7 @@ size_t machine__fprintf(struct machine *machine, FILE *fp)
 			ret += thread__fprintf(pos, fp);
 		}
 
-		pthread_rwlock_unlock(&threads->lock);
+		up_read(&threads->lock);
 	}
 	return ret;
 }
@@ -1319,7 +1320,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 		struct dso *kernel = NULL;
 		struct dso *dso;
 
-		pthread_rwlock_rdlock(&machine->dsos.lock);
+		down_read(&machine->dsos.lock);
 
 		list_for_each_entry(dso, &machine->dsos.head, node) {
 
@@ -1349,7 +1350,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 			break;
 		}
 
-		pthread_rwlock_unlock(&machine->dsos.lock);
+		up_read(&machine->dsos.lock);
 
 		if (kernel == NULL)
 			kernel = machine__findnew_dso(machine, kmmap_prefix);
@@ -1513,7 +1514,7 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
 
 	BUG_ON(refcount_read(&th->refcnt) == 0);
 	if (lock)
-		pthread_rwlock_wrlock(&threads->lock);
+		down_write(&threads->lock);
 	rb_erase_init(&th->rb_node, &threads->entries);
 	RB_CLEAR_NODE(&th->rb_node);
 	--threads->nr;
@@ -1524,7 +1525,7 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
 	 */
 	list_add_tail(&th->node, &threads->dead);
 	if (lock)
-		pthread_rwlock_unlock(&threads->lock);
+		up_write(&threads->lock);
 	thread__put(th);
 }