[RFC PATCH v2 net-next 02/12] sfc: batch up RX delivery

[Edward Cree <ecree@solarflare.com>]

Improves packet rate of 1-byte UDP receives by up to 10%.

Signed-off-by: Edward Cree <ecree@solarflare.com>
---
 drivers/net/ethernet/sfc/efx.c        | 12 ++++++++++++
 drivers/net/ethernet/sfc/net_driver.h |  3 +++
 drivers/net/ethernet/sfc/rx.c         |  7 ++++++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index ad4a354ce570..e84e4437dbbd 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -264,11 +264,17 @@ static int efx_check_disabled(struct efx_nic *efx)
 static int efx_process_channel(struct efx_channel *channel, int budget)
 {
 	struct efx_tx_queue *tx_queue;
+	struct sk_buff_head rx_list;
 	int spent;
 
 	if (unlikely(!channel->enabled))
 		return 0;
 
+	/* Prepare the batch receive list */
+	EFX_WARN_ON_PARANOID(channel->rx_list != NULL);
+	channel->rx_list = &rx_list;
+	__skb_queue_head_init(channel->rx_list);
+
 	efx_for_each_channel_tx_queue(tx_queue, channel) {
 		tx_queue->pkts_compl = 0;
 		tx_queue->bytes_compl = 0;
@@ -291,6 +297,10 @@ static int efx_process_channel(struct efx_channel *channel, int budget)
 		}
 	}
 
+	/* Receive any packets we queued up */
+	netif_receive_skb_list(channel->rx_list);
+	channel->rx_list = NULL;
+
 	return spent;
 }
 
@@ -555,6 +565,8 @@ static int efx_probe_channel(struct efx_channel *channel)
 			goto fail;
 	}
 
+	channel->rx_list = NULL;
+
 	return 0;
 
 fail:
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 65568925c3ef..e1d3ca3b90b5 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -448,6 +448,7 @@ enum efx_sync_events_state {
  *	__efx_rx_packet(), or zero if there is none
  * @rx_pkt_index: Ring index of first buffer for next packet to be delivered
  *	by __efx_rx_packet(), if @rx_pkt_n_frags != 0
+ * @rx_list: list of SKBs from current RX, awaiting processing
  * @rx_queue: RX queue for this channel
  * @tx_queue: TX queues for this channel
  * @sync_events_state: Current state of sync events on this channel
@@ -500,6 +501,8 @@ struct efx_channel {
 	unsigned int rx_pkt_n_frags;
 	unsigned int rx_pkt_index;
 
+	struct sk_buff_head *rx_list;
+
 	struct efx_rx_queue rx_queue;
 	struct efx_tx_queue tx_queue[EFX_TXQ_TYPES];
 
diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
index d2e254f2f72b..3e4d67d2d45d 100644
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -634,7 +634,12 @@ static void efx_rx_deliver(struct efx_channel *channel, u8 *eh,
 			return;
 
 	/* Pass the packet up */
-	netif_receive_skb(skb);
+	if (channel->rx_list != NULL)
+		/* Add to list, will pass up later */
+		__skb_queue_tail(channel->rx_list, skb);
+	else
+		/* No list, so pass it up now */
+		netif_receive_skb(skb);
 }
 
 /* Handle a received packet.  Second half: Touches packet payload. */