--- //depot/vendor/freebsd_7/src/sys/kern/kern_synch.c	2007/05/31 19:36:45
+++ //depot/yahoo/ybsd_7/src/sys/kern/kern_synch.c	2007/06/06 10:51:41
@@ -365,6 +366,18 @@
 }
 
 /*
+ * Returns true if it was able to find an in-memory thread to wake up.
+ */
+int
+wakeup_just_one(ident)
+	register void *ident;
+{
+
+	sleepq_lock(ident);
+	return (sleepq_signal(ident, SLEEPQ_SLEEP | SLEEPQ_JUST_ONE, -1, 0));
+}
+
+/*
  * The machine independent parts of context switching.
  */
 void
--- //depot/vendor/freebsd_7/src/sys/kern/subr_sleepqueue.c	2007/05/18 00:35:26
+++ //depot/yahoo/ybsd_7/src/sys/kern/subr_sleepqueue.c	2007/06/06 09:38:19
@@ -704,7 +705,7 @@
 /*
  * Find the highest priority thread sleeping on a wait channel and resume it.
  */
-void
+int
 sleepq_signal(void *wchan, int flags, int pri, int queue)
 {
 	struct sleepqueue *sq;
@@ -716,11 +717,34 @@
 	sq = sleepq_lookup(wchan);
 	if (sq == NULL) {
 		sleepq_release(wchan);
-		return;
+		return (0);
 	}
 	KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
 	    ("%s: mismatch between sleep/wakeup and cv_*", __func__));
 
+	if (flags & SLEEPQ_JUST_ONE) {
+		/*
+		 * Find the thread that has been sleeping the shortest
+		 * amount of time and that is not swapped out.  We hold
+		 * sched_lock during this whole traversal to make sure the
+		 * thread we pick doesn't get swapped out while we are
+		 * picking it.
+		 */
+		mtx_lock_spin(&sched_lock);
+		besttd = TAILQ_LAST(&sq->sq_blocked[queue], threadqueue);
+		TAILQ_FOREACH_REVERSE(td, &sq->sq_blocked[queue], threadqueue, td_slpq) {
+			if (td->td_proc->p_sflag & PS_INMEM) {
+				besttd = td;
+				break;
+			}
+		}
+		if (besttd != NULL)
+			sleepq_resume_thread(sq, besttd, pri);
+		mtx_unlock_spin(&sched_lock);
+		sleepq_release(wchan);
+		return (besttd != NULL);
+	}
+
 	/*
 	 * Find the highest priority thread on the queue.  If there is a
 	 * tie, use the thread that first appears in the queue as it has
@@ -737,6 +761,7 @@
 	sleepq_resume_thread(sq, besttd, pri);
 	mtx_unlock_spin(&sched_lock);
 	sleepq_release(wchan);
+	return (1);
 }
 
 /*
--- //depot/vendor/freebsd_7/src/sys/kern/uipc_socket.c	2007/05/31 19:36:45
+++ //depot/yahoo/ybsd_7/src/sys/kern/uipc_socket.c	2007/06/06 14:56:59
@@ -2843,8 +2844,9 @@
 			head->so_qlen++;
 			so->so_qstate |= SQ_COMP;
 			ACCEPT_UNLOCK();
-			sorwakeup(head);
-			wakeup_one(&head->so_timeo);
+			if (!wakeup_just_one(&head->so_timeo)) {
+				sorwakeup(head);
+			}
 		} else {
 			ACCEPT_UNLOCK();
 			so->so_upcall =
--- //depot/vendor/freebsd_7/src/sys/sys/sleepqueue.h	2007/03/31 17:35:54
+++ //depot/yahoo/ybsd_7/src/sys/sys/sleepqueue.h	2007/06/06 09:38:19
@@ -88,6 +89,7 @@
 #define	SLEEPQ_PAUSE		0x02		/* Used by pause. */
 #define	SLEEPQ_SX		0x03		/* Used by an sx lock. */
 #define	SLEEPQ_INTERRUPTIBLE	0x100		/* Sleep is interruptible. */
+#define	SLEEPQ_JUST_ONE		0x200		/* Alternate signal semantics */
 
 void	init_sleepqueues(void);
 void	sleepq_abort(struct thread *td, int intrval);
@@ -100,7 +102,7 @@
 struct sleepqueue *sleepq_lookup(void *wchan);
 void	sleepq_release(void *wchan);
 void	sleepq_remove(struct thread *td, void *wchan);
-void	sleepq_signal(void *wchan, int flags, int pri, int queue);
+int	sleepq_signal(void *wchan, int flags, int pri, int queue);
 void	sleepq_set_timeout(void *wchan, int timo);
 int	sleepq_timedwait(void *wchan);
 int	sleepq_timedwait_sig(void *wchan);