diff --git a/sys/dev/cxgb/cxgb_main.c b/sys/dev/cxgb/cxgb_main.c
index 3a49146d24c..206c537029e 100644
--- a/sys/dev/cxgb/cxgb_main.c
+++ b/sys/dev/cxgb/cxgb_main.c
@@ -1607,6 +1607,11 @@ cxgb_start_tx(struct ifnet *ifp, uint32_t txmax)
 	if (err == 0 && m == NULL)
 		err = ENOBUFS;
 
+	if ((err == 0) &&  (txq->size <= txq->in_use + TX_MAX_DESC) &&
+	    (ifp->if_drv_flags & IFF_DRV_OACTIVE) == 0) {
+		ifp->if_drv_flags |= IFF_DRV_OACTIVE;
+		err = ENOSPC;
+	}
 	return (err);
 }
 
diff --git a/sys/dev/cxgb/cxgb_sge.c b/sys/dev/cxgb/cxgb_sge.c
index aaced451655..d8a1ce5e25a 100644
--- a/sys/dev/cxgb/cxgb_sge.c
+++ b/sys/dev/cxgb/cxgb_sge.c
@@ -766,6 +766,11 @@ sge_timer_reclaim(void *arg, int ncount)
 			for (i = 0; i < n; i++) {
 				m_freem_vec(m_vec[i]);
 			}
+			if (qs->port->ifp->if_drv_flags & IFF_DRV_OACTIVE &&
+			    txq->size - txq->in_use >= TX_START_MAX_DESC) {
+				qs->port->ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
+				taskqueue_enqueue(qs->port->tq, &qs->port->start_task);
+			}
 		} 
 		    
 		txq = &qs->txq[TXQ_OFLD];