Index: sys/dev/hyperv/vmbus/hv_channel_mgmt.c
===================================================================
--- sys/dev/hyperv/vmbus/hv_channel_mgmt.c
+++ sys/dev/hyperv/vmbus/hv_channel_mgmt.c
@@ -271,14 +271,16 @@
 	boolean_t		f_new;
 	hv_vmbus_channel*	channel;
 	int			ret;
+	uint32_t                relid;
 
 	f_new = TRUE;
 	channel = NULL;
-
+	relid = new_channel->offer_msg.child_rel_id;
 	/*
 	 * Make sure this is a new offer
 	 */
 	mtx_lock(&hv_vmbus_g_connection.channel_lock);
+	hv_vmbus_g_connection.channels[relid] = (void *)new_channel;
 
 	TAILQ_FOREACH(channel, &hv_vmbus_g_connection.channel_anchor,
 	    list_entry)
@@ -322,8 +324,9 @@
 			mtx_unlock(&channel->sc_lock);
 
 			/* Insert new channel into channel_anchor. */
-			printf("Storvsc get multi-channel offer, rel=%u.\n",
-			    new_channel->offer_msg.child_rel_id);	
+			printf("VMBUS get multi-channel offer, rel=%u,sub=%u\n",
+			    new_channel->offer_msg.child_rel_id,
+			    new_channel->offer_msg.offer.sub_channel_index);	
 			mtx_lock(&hv_vmbus_g_connection.channel_lock);
 			TAILQ_INSERT_TAIL(&hv_vmbus_g_connection.channel_anchor,
 			    new_channel, list_entry);				
@@ -330,8 +333,9 @@
 			mtx_unlock(&hv_vmbus_g_connection.channel_lock);
 
 			if(bootverbose)
-				printf("VMBUS: new multi-channel offer <%p>.\n",
-				    new_channel);
+				printf("VMBUS: new multi-channel offer <%p>, "
+				    "its primary channel is <%p>.\n",
+				    new_channel, new_channel->primary_channel);
 
 			/*XXX add it to percpu_list */
 
@@ -521,11 +525,14 @@
 
 	rescind = (hv_vmbus_channel_rescind_offer*) hdr;
 
-	channel = hv_vmbus_get_channel_from_rel_id(rescind->child_rel_id);
+	channel = hv_vmbus_g_connection.channels[rescind->child_rel_id];
 	if (channel == NULL) 
 	    return;
 
 	hv_vmbus_child_device_unregister(channel->device);
+	mtx_lock(&hv_vmbus_g_connection.channel_lock);
+	hv_vmbus_g_connection.channels[rescind->child_rel_id] = NULL;
+	mtx_unlock(&hv_vmbus_g_connection.channel_lock);
 }
 
 /**
@@ -779,6 +786,8 @@
 	    hv_vmbus_child_device_unregister(channel->device);
 	    hv_vmbus_free_vmbus_channel(channel);
 	}
+	bzero(hv_vmbus_g_connection.channels, 
+		sizeof(hv_vmbus_channel*) * HV_CHANNEL_MAX_COUNT);
 	mtx_unlock(&hv_vmbus_g_connection.channel_lock);
 }
 
Index: sys/dev/hyperv/vmbus/hv_connection.c
===================================================================
--- sys/dev/hyperv/vmbus/hv_connection.c
+++ sys/dev/hyperv/vmbus/hv_connection.c
@@ -229,6 +229,13 @@
 	    goto cleanup;
 	}
 
+	hv_vmbus_g_connection.channels = malloc(sizeof(hv_vmbus_channel*) *
+		HV_CHANNEL_MAX_COUNT,
+		M_DEVBUF, M_NOWAIT | M_ZERO);
+	if (hv_vmbus_g_connection.channels == NULL) {
+	    ret = ENOMEM;
+	    goto cleanup;
+	}
 	/*
 	 * Find the highest vmbus version number we can support.
 	 */
@@ -292,6 +299,7 @@
 		free(msg_info, M_DEVBUF);
 	}
 
+	free(hv_vmbus_g_connection.channels, M_DEVBUF);
 	return (ret);
 }
 
@@ -322,6 +330,7 @@
 	hv_work_queue_close(hv_vmbus_g_connection.work_queue);
 	sema_destroy(&hv_vmbus_g_connection.control_sema);
 
+	free(hv_vmbus_g_connection.channels, M_DEVBUF);
 	hv_vmbus_g_connection.connect_state = HV_DISCONNECTED;
 
 	free(msg, M_DEVBUF);
@@ -330,35 +339,6 @@
 }
 
 /**
- * Get the channel object given its child relative id (ie channel id)
- */
-hv_vmbus_channel*
-hv_vmbus_get_channel_from_rel_id(uint32_t rel_id) {
-
-	hv_vmbus_channel* channel;
-	hv_vmbus_channel* foundChannel = NULL;
-
-	/*
-	 * TODO:
-	 * Consider optimization where relids are stored in a fixed size array
-	 *  and channels are accessed without the need to take this lock or search
-	 *  the list.
-	 */
-	mtx_lock(&hv_vmbus_g_connection.channel_lock);
-	TAILQ_FOREACH(channel,
-		&hv_vmbus_g_connection.channel_anchor, list_entry) {
-
-	    if (channel->offer_msg.child_rel_id == rel_id) {
-		foundChannel = channel;
-		break;
-	    }
-	}
-	mtx_unlock(&hv_vmbus_g_connection.channel_lock);
-
-	return (foundChannel);
-}
-
-/**
  * Process a channel event notification
  */
 static void
@@ -374,7 +354,7 @@
 	 * the channel callback to process the event
 	 */
 
-	channel = hv_vmbus_get_channel_from_rel_id(relid);
+	channel = hv_vmbus_g_connection.channels[relid];
 
 	if (channel == NULL) {
 		return;
@@ -470,7 +450,7 @@
 	if (recv_interrupt_page != NULL) {
 	    for (dword = 0; dword < maxdword; dword++) {
 		if (recv_interrupt_page[dword]) {
-		    for (bit = 0; bit < 32; bit++) {
+		    for (bit = 0; bit < HV_CHANNEL_DWORD_LEN; bit++) {
 			if (synch_test_and_clear_bit(bit,
 			    (uint32_t *) &recv_interrupt_page[dword])) {
 			    rel_id = (dword << 5) + bit;
Index: sys/dev/hyperv/vmbus/hv_vmbus_priv.h
===================================================================
--- sys/dev/hyperv/vmbus/hv_vmbus_priv.h
+++ sys/dev/hyperv/vmbus/hv_vmbus_priv.h
@@ -58,6 +58,12 @@
 #define HV_EVENT_FLAGS_BYTE_COUNT   (256)
 #define HV_EVENT_FLAGS_DWORD_COUNT  (256 / sizeof(uint32_t))
 
+/**
+ * max channel count <== event_flags_dword_count * bit_of_dword
+ */
+#define HV_CHANNEL_DWORD_LEN        (32)
+#define HV_CHANNEL_MAX_COUNT        \
+	((HV_EVENT_FLAGS_DWORD_COUNT) * HV_CHANNEL_DWORD_LEN)
 /*
  * MessageId: HV_STATUS_INSUFFICIENT_BUFFERS
  * MessageText:
@@ -355,6 +361,10 @@
 	TAILQ_HEAD(, hv_vmbus_channel)		channel_anchor;
 	struct mtx				channel_lock;
 
+	/**
+	 * channel table for fast lookup through id.
+	 */
+	hv_vmbus_channel                        **channels;
 	hv_vmbus_handle				work_queue;
 	struct sema				control_sema;
 } hv_vmbus_connection;
@@ -699,7 +709,6 @@
 					struct hv_device *child_dev);
 int			hv_vmbus_child_device_unregister(
 					struct hv_device *child_dev);
-hv_vmbus_channel*	hv_vmbus_get_channel_from_rel_id(uint32_t rel_id);
 
 /**
  * Connection interfaces