[PATCH] xen-netfront: rearrange netfront_info structure to separate tx and rx

Keep tx and rx elements separate on different cachelines to prevent
bouncing.

Signed-off-by: Jeremy Fitzhardinge <redacted>
Cc: Stephen Hemminger <redacted>
Cc: Christoph Hellwig <hch@infradead.org>

---
 drivers/net/xen-netfront.c |   37 ++++++++++++++++++-------------------
 1 file changed, 18 insertions(+), 19 deletions(-)

===================================================================

--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c

@@ -72,22 +72,12 @@ struct netfront_info {
 	struct list_head list;
 	struct net_device *netdev;
 
+	unsigned int evtchn;
+	struct xenbus_device *xbdev;
+
+	spinlock_t   tx_lock;
 	struct xen_netif_tx_front_ring tx;
-	struct xen_netif_rx_front_ring rx;
-
-	spinlock_t   tx_lock;
-	spinlock_t   rx_lock;
-
-	unsigned int evtchn;
-
-	/* Receive-ring batched refills. */
-#define RX_MIN_TARGET 8
-#define RX_DFL_MIN_TARGET 64
-#define RX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
-	unsigned rx_min_target, rx_max_target, rx_target;
-	struct sk_buff_head rx_batch;
-
-	struct timer_list rx_refill_timer;
+	int tx_ring_ref;
 
 	/*
 	 * {tx,rx}_skbs store outstanding skbuffs. Free tx_skb entries

@@ -106,13 +96,22 @@ struct netfront_info {
 	grant_ref_t grant_tx_ref[NET_TX_RING_SIZE];
 	unsigned tx_skb_freelist;
 
+	spinlock_t   rx_lock ____cacheline_aligned_in_smp;
+	struct xen_netif_rx_front_ring rx;
+	int rx_ring_ref;
+
+	/* Receive-ring batched refills. */
+#define RX_MIN_TARGET 8
+#define RX_DFL_MIN_TARGET 64
+#define RX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
+	unsigned rx_min_target, rx_max_target, rx_target;
+	struct sk_buff_head rx_batch;
+
+	struct timer_list rx_refill_timer;
+
 	struct sk_buff *rx_skbs[NET_RX_RING_SIZE];
 	grant_ref_t gref_rx_head;
 	grant_ref_t grant_rx_ref[NET_RX_RING_SIZE];
-
-	struct xenbus_device *xbdev;
-	int tx_ring_ref;
-	int rx_ring_ref;
 
 	unsigned long rx_pfn_array[NET_RX_RING_SIZE];
 	struct multicall_entry rx_mcl[NET_RX_RING_SIZE+1];

Jeremy Fitzhardinge wrote:

Keep tx and rx elements separate on different cachelines to prevent
bouncing.

Signed-off-by: Jeremy Fitzhardinge <redacted>
Cc: Stephen Hemminger <redacted>
Cc: Christoph Hellwig <hch@infradead.org>

---
 drivers/net/xen-netfront.c |   37 ++++++++++++++++++-------------------
 1 file changed, 18 insertions(+), 19 deletions(-)

ACK but does not apply to jgarzik/netdev-2.6.git#upstream nor 
davem/net-2.6.24.git

Jeff Garzik wrote:

Jeremy Fitzhardinge wrote:

quoted

Keep tx and rx elements separate on different cachelines to prevent
bouncing.

Signed-off-by: Jeremy Fitzhardinge <redacted>
Cc: Stephen Hemminger <redacted>
Cc: Christoph Hellwig <hch@infradead.org>

---
 drivers/net/xen-netfront.c |   37 ++++++++++++++++++-------------------
 1 file changed, 18 insertions(+), 19 deletions(-)

ACK but does not apply to jgarzik/netdev-2.6.git#upstream nor
davem/net-2.6.24.git 

Oh, OK, I'll have a look.  I wasn't aware of any other changes in
xen-netfront.  Or rather, there are a couple of other changes which I
think you already have: one to use the common netdev stats structure,
and another to remove a chunk of dead code.

    J

Jeff Garzik wrote:

ACK but does not apply to jgarzik/netdev-2.6.git#upstream nor
davem/net-2.6.24.git 

OK, looks like you don't have the other two patches.  Will post in a sec.

    J