Index: head/sys/dev/hyperv/vmbus/vmbus_chan.c
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chan.c
+++ head/sys/dev/hyperv/vmbus/vmbus_chan.c
@@ -83,7 +83,7 @@
 vmbus_chan_signal_tx(const struct hv_vmbus_channel *chan)
 {
 	atomic_set_long(chan->ch_evtflag, chan->ch_evtflag_mask);
-	if (chan->ch_flags & VMBUS_CHAN_FLAG_HASMNF)
+	if (chan->ch_txflags & VMBUS_CHAN_TXF_HASMNF)
 		atomic_set_int(chan->ch_montrig, chan->ch_montrig_mask);
 	else
 		hypercall_signal_event(chan->ch_monprm_dma.hv_paddr);
@@ -95,7 +95,7 @@
 	struct hv_vmbus_channel *chan = arg1;
 	int mnf = 0;
 
-	if (chan->ch_flags & VMBUS_CHAN_FLAG_HASMNF)
+	if (chan->ch_txflags & VMBUS_CHAN_TXF_HASMNF)
 		mnf = 1;
 	return sysctl_handle_int(oidp, &mnf, 0, req);
 }
@@ -1102,7 +1102,7 @@
 		/*
 		 * Setup MNF stuffs.
 		 */
-		chan->ch_flags |= VMBUS_CHAN_FLAG_HASMNF;
+		chan->ch_txflags |= VMBUS_CHAN_TXF_HASMNF;
 
 		trig_idx = offer->chm_montrig / VMBUS_MONTRIG_LEN;
 		if (trig_idx >= VMBUS_MONTRIGS_MAX)
Index: head/sys/dev/hyperv/vmbus/vmbus_chanvar.h
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chanvar.h
+++ head/sys/dev/hyperv/vmbus/vmbus_chanvar.h
@@ -71,42 +71,63 @@
 } hv_vmbus_ring_buffer_info;
 
 typedef struct hv_vmbus_channel {
-	device_t			ch_dev;
-	struct vmbus_softc		*ch_vmbus;
+	/*
+	 * NOTE:
+	 * Fields before ch_txbr are only accessed on this channel's
+	 * target CPU.
+	 */
 	uint32_t			ch_flags;	/* VMBUS_CHAN_FLAG_ */
-	uint32_t			ch_id;		/* channel id */
+
+	/*
+	 * RX bufring; immediately following ch_txbr.
+	 */
+	hv_vmbus_ring_buffer_info	ch_rxbr;
+
+	struct taskqueue		*ch_tq;
+	struct task			ch_task;
+	vmbus_chan_callback_t		ch_cb;
+	void				*ch_cbarg;
+
+	/*
+	 * TX bufring; at the beginning of ch_bufring.
+	 *
+	 * NOTE:
+	 * Put TX bufring and the following MNF/evtflag to a new
+	 * cacheline, since they will be accessed on all CPUs by
+	 * locking ch_txbr first.
+	 *
+	 * XXX
+	 * TX bufring and following MNF/evtflags do _not_ fit in
+	 * one 64B cacheline.
+	 */
+	hv_vmbus_ring_buffer_info	ch_txbr __aligned(CACHE_LINE_SIZE);
+	uint32_t			ch_txflags;	/* VMBUS_CHAN_TXF_ */
 
 	/*
 	 * These are based on the vmbus_chanmsg_choffer.chm_montrig.
 	 * Save it here for easy access.
 	 */
-	volatile uint32_t		*ch_montrig;	/* MNF trigger loc. */
 	uint32_t			ch_montrig_mask;/* MNF trig mask */
+	volatile uint32_t		*ch_montrig;	/* MNF trigger loc. */
 
 	/*
 	 * These are based on the vmbus_chanmsg_choffer.chm_chanid.
 	 * Save it here for easy access.
 	 */
-	volatile u_long			*ch_evtflag;	/* event flag loc. */
 	u_long				ch_evtflag_mask;/* event flag */
+	volatile u_long			*ch_evtflag;	/* event flag loc. */
 
 	/*
-	 * TX bufring; at the beginning of ch_bufring.
-	 */
-	hv_vmbus_ring_buffer_info	ch_txbr;
-	/*
-	 * RX bufring; immediately following ch_txbr.
+	 * Rarely used fields.
 	 */
-	hv_vmbus_ring_buffer_info	ch_rxbr;
-
-	struct taskqueue		*ch_tq;
-	struct task			ch_task;
-	vmbus_chan_callback_t		ch_cb;
-	void				*ch_cbarg;
 
 	struct hyperv_mon_param		*ch_monprm;
 	struct hyperv_dma		ch_monprm_dma;
 
+	uint32_t			ch_id;		/* channel id */
+	device_t			ch_dev;
+	struct vmbus_softc		*ch_vmbus;
+
 	int				ch_cpuid;	/* owner cpu */
 	/*
 	 * Virtual cpuid for ch_cpuid; it is used to communicate cpuid
@@ -141,11 +162,10 @@
 	struct hyperv_guid		ch_guid_inst;
 
 	struct sysctl_ctx_list		ch_sysctl_ctx;
-} hv_vmbus_channel;
+} hv_vmbus_channel __aligned(CACHE_LINE_SIZE);
 
 #define VMBUS_CHAN_ISPRIMARY(chan)	((chan)->ch_subidx == 0)
 
-#define VMBUS_CHAN_FLAG_HASMNF		0x0001
 /*
  * If this flag is set, this channel's interrupt will be masked in ISR,
  * and the RX bufring will be drained before this channel's interrupt is
@@ -156,6 +176,8 @@
  */
 #define VMBUS_CHAN_FLAG_BATCHREAD	0x0002
 
+#define VMBUS_CHAN_TXF_HASMNF		0x0001
+
 #define VMBUS_CHAN_ST_OPENED_SHIFT	0
 #define VMBUS_CHAN_ST_OPENED		(1 << VMBUS_CHAN_ST_OPENED_SHIFT)