commit 4e632d533674b9f2cceea61ef1ac1036c965f94e
Author: Mikolaj Golub <trociny@freebsd.org>
Date:   Wed Dec 4 23:24:21 2013 +0200

    Send wakeup to threads waiting on empty queue before releasing the
    lock to decrease spurious wakeups.
    
    Submitted by:	davidxu

diff --git a/sbin/hastd/primary.c b/sbin/hastd/primary.c
index 3f1ca92..74ed799 100644
--- a/sbin/hastd/primary.c
+++ b/sbin/hastd/primary.c
@@ -179,28 +179,22 @@ static pthread_mutex_t metadata_lock;
 #define	ISCONNECTED(res, no)	\
 	((res)->hr_remotein != NULL && (res)->hr_remoteout != NULL)
 
-#define	QUEUE_INSERT1(hio, name, ncomp)	do {				\
-	bool _wakeup;							\
-									\
+#define QUEUE_INSERT1(hio, name, ncomp) do {				\
 	mtx_lock(&hio_##name##_list_lock[(ncomp)]);			\
-	_wakeup = TAILQ_EMPTY(&hio_##name##_list[(ncomp)]);		\
+	if (TAILQ_EMPTY(&hio_##name##_list[(ncomp)]))			\
+		cv_broadcast(&hio_##name##_list_cond[(ncomp)]);		\
 	TAILQ_INSERT_TAIL(&hio_##name##_list[(ncomp)], (hio),		\
 	    hio_next[(ncomp)]);						\
 	hio_##name##_list_size[(ncomp)]++;				\
-	mtx_unlock(&hio_##name##_list_lock[ncomp]);			\
-	if (_wakeup)							\
-		cv_broadcast(&hio_##name##_list_cond[(ncomp)]);		\
+	mtx_unlock(&hio_##name##_list_lock[(ncomp)]);			\
 } while (0)
 #define	QUEUE_INSERT2(hio, name)	do {				\
-	bool _wakeup;							\
-									\
 	mtx_lock(&hio_##name##_list_lock);				\
-	_wakeup = TAILQ_EMPTY(&hio_##name##_list);			\
+	if (TAILQ_EMPTY(&hio_##name##_list))				\
+		cv_broadcast(&hio_##name##_list_cond);			\
 	TAILQ_INSERT_TAIL(&hio_##name##_list, (hio), hio_##name##_next);\
 	hio_##name##_list_size++;					\
 	mtx_unlock(&hio_##name##_list_lock);				\
-	if (_wakeup)							\
-		cv_broadcast(&hio_##name##_list_cond);			\
 } while (0)
 #define	QUEUE_TAKE1(hio, name, ncomp, timeout)	do {			\
 	bool _last;							\
diff --git a/sbin/hastd/secondary.c b/sbin/hastd/secondary.c
index d9d73d9..1ddd1f2 100644
--- a/sbin/hastd/secondary.c
+++ b/sbin/hastd/secondary.c
@@ -110,15 +110,12 @@ static void *disk_thread(void *arg);
 static void *send_thread(void *arg);
 
 #define	QUEUE_INSERT(name, hio)	do {					\
-	bool _wakeup;							\
-									\
 	mtx_lock(&hio_##name##_list_lock);				\
-	_wakeup = TAILQ_EMPTY(&hio_##name##_list);			\
+	if (TAILQ_EMPTY(&hio_##name##_list))				\
+		cv_broadcast(&hio_##name##_list_cond);			\
 	TAILQ_INSERT_TAIL(&hio_##name##_list, (hio), hio_next);		\
 	hio_##name##_list_size++;					\
 	mtx_unlock(&hio_##name##_list_lock);				\
-	if (_wakeup)							\
-		cv_broadcast(&hio_##name##_list_cond);			\
 } while (0)
 #define	QUEUE_TAKE(name, hio)	do {					\
 	mtx_lock(&hio_##name##_list_lock);				\