2 files changed, 121 insertions, 1 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0e65b80927b7..517520ae1520 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -170,6 +170,11 @@ static inline pid_t gettid(void)
 }
 #endif
 
+static int record__threads_enabled(struct record *rec)
+{
+	return rec->opts.threads_spec;
+}
+
 static bool switch_output_signal(struct record *rec)
 {
 	return rec->switch_output.signal &&
@@ -1473,6 +1478,68 @@ static void record__thread_munmap_filtered(struct fdarray *fda, int fd,
 		perf_mmap__put(map);
 }
 
+static void *record__thread(void *arg)
+{
+	enum thread_msg msg = THREAD_MSG__READY;
+	bool terminate = false;
+	struct fdarray *pollfd;
+	int err, ctlfd_pos;
+
+	thread = arg;
+	thread->tid = gettid();
+
+	err = write(thread->pipes.ack[1], &msg, sizeof(msg));
+	if (err == -1)
+		pr_warning("threads[%d]: failed to notify on start: %s\n",
+			   thread->tid, strerror(errno));
+
+	pr_debug("threads[%d]: started on cpu%d\n", thread->tid, sched_getcpu());
+
+	pollfd = &thread->pollfd;
+	ctlfd_pos = thread->ctlfd_pos;
+
+	for (;;) {
+		unsigned long long hits = thread->samples;
+
+		if (record__mmap_read_all(thread->rec, false) < 0 || terminate)
+			break;
+
+		if (hits == thread->samples) {
+
+			err = fdarray__poll(pollfd, -1);
+			/*
+			 * Propagate error, only if there's any. Ignore positive
+			 * number of returned events and interrupt error.
+			 */
+			if (err > 0 || (err < 0 && errno == EINTR))
+				err = 0;
+			thread->waking++;
+
+			if (fdarray__filter(pollfd, POLLERR | POLLHUP,
+					    record__thread_munmap_filtered, NULL) == 0)
+				break;
+		}
+
+		if (pollfd->entries[ctlfd_pos].revents & POLLHUP) {
+			terminate = true;
+			close(thread->pipes.msg[0]);
+			thread->pipes.msg[0] = -1;
+			pollfd->entries[ctlfd_pos].fd = -1;
+			pollfd->entries[ctlfd_pos].events = 0;
+		}
+
+		pollfd->entries[ctlfd_pos].revents = 0;
+	}
+	record__mmap_read_all(thread->rec, true);
+
+	err = write(thread->pipes.ack[1], &msg, sizeof(msg));
+	if (err == -1)
+		pr_warning("threads[%d]: failed to notify on termination: %s\n",
+			   thread->tid, strerror(errno));
+
+	return NULL;
+}
+
 static void record__init_features(struct record *rec)
 {
 	struct perf_session *session = rec->session;
@@ -1916,13 +1983,65 @@ static int record__terminate_thread(struct record_thread *thread_data)
 
 static int record__start_threads(struct record *rec)
 {
+	int t, tt, err, ret = 0, nr_threads = rec->nr_threads;
 	struct record_thread *thread_data = rec->thread_data;
+	sigset_t full, mask;
+	pthread_t handle;
+	pthread_attr_t attrs;
 
 	thread = &thread_data[0];
 
+	if (!record__threads_enabled(rec))
+		return 0;
+
+	sigfillset(&full);
+	if (sigprocmask(SIG_SETMASK, &full, &mask)) {
+		pr_err("Failed to block signals on threads start: %s\n", strerror(errno));
+		return -1;
+	}
+
+	pthread_attr_init(&attrs);
+	pthread_attr_setdetachstate(&attrs, PTHREAD_CREATE_DETACHED);
+
+	for (t = 1; t < nr_threads; t++) {
+		enum thread_msg msg = THREAD_MSG__UNDEFINED;
+
+#ifdef HAVE_PTHREAD_ATTR_SETAFFINITY_NP
+		pthread_attr_setaffinity_np(&attrs,
+					    MMAP_CPU_MASK_BYTES(&(thread_data[t].mask->affinity)),
+					    (cpu_set_t *)(thread_data[t].mask->affinity.bits));
+#endif
+		if (pthread_create(&handle, &attrs, record__thread, &thread_data[t])) {
+			for (tt = 1; tt < t; tt++)
+				record__terminate_thread(&thread_data[t]);
+			pr_err("Failed to start threads: %s\n", strerror(errno));
+			ret = -1;
+			goto out_err;
+		}
+
+		err = read(thread_data[t].pipes.ack[0], &msg, sizeof(msg));
+		if (err > 0)
+			pr_debug2("threads[%d]: sent %s\n", rec->thread_data[t].tid,
+				  thread_msg_tags[msg]);
+		else
+			pr_warning("threads[%d]: failed to receive start notification from %d\n",
+				   thread->tid, rec->thread_data[t].tid);
+	}
+
+	sched_setaffinity(0, MMAP_CPU_MASK_BYTES(&thread->mask->affinity),
+			(cpu_set_t *)thread->mask->affinity.bits);
+
 	pr_debug("threads[%d]: started on cpu%d\n", thread->tid, sched_getcpu());
 
-	return 0;
+out_err:
+	pthread_attr_destroy(&attrs);
+
+	if (sigprocmask(SIG_SETMASK, &mask, NULL)) {
+		pr_err("Failed to unblock signals on threads start: %s\n", strerror(errno));
+		ret = -1;
+	}
+
+	return ret;
 }
 
 static int record__stop_threads(struct record *rec)
diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index ef6c2715fdd9..ad08c092f3dd 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -78,6 +78,7 @@ struct record_opts {
 	int	      ctl_fd_ack;
 	bool	      ctl_fd_close;
 	int	      synth;
+	int	      threads_spec;
 };
 
 extern const char * const *record_usage;