netdev - [RFC PATCH net-next 2/4] sfc: use batched receive for GRO

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Message-ID: <22d53c32-1c4d-0b29-900a-d006e23a0bd9@solarflare.com>
Date:   Thu, 30 Aug 2018 21:00:11 +0100
From:   Edward Cree <ecree@...arflare.com>
To:     <linux-net-drivers@...arflare.com>, <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>
Subject: [RFC PATCH net-next 2/4] sfc: use batched receive for GRO

Signed-off-by: Edward Cree <ecree@...arflare.com>
---
 drivers/net/ethernet/sfc/efx.c        | 11 +++++++++--
 drivers/net/ethernet/sfc/net_driver.h |  1 +
 drivers/net/ethernet/sfc/rx.c         | 16 +++++++++++++---
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 330233286e78..dba13a28014c 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -263,9 +263,9 @@ static int efx_check_disabled(struct efx_nic *efx)
  */
 static int efx_process_channel(struct efx_channel *channel, int budget)
 {
+	struct list_head rx_list, gro_list;
 	struct efx_tx_queue *tx_queue;
-	struct list_head rx_list;
-	int spent;
+	int spent, gro_count;
 
 	if (unlikely(!channel->enabled))
 		return 0;
@@ -275,6 +275,10 @@ static int efx_process_channel(struct efx_channel *channel, int budget)
 	INIT_LIST_HEAD(&rx_list);
 	channel->rx_list = &rx_list;
 
+	EFX_WARN_ON_PARANOID(channel->gro_list != NULL);
+	INIT_LIST_HEAD(&gro_list);
+	channel->gro_list = &gro_list;
+
 	efx_for_each_channel_tx_queue(tx_queue, channel) {
 		tx_queue->pkts_compl = 0;
 		tx_queue->bytes_compl = 0;
@@ -300,6 +304,9 @@ 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;
+	gro_count = napi_gro_receive_list(&channel->napi_str, channel->gro_list);
+	channel->irq_mod_score += gro_count * 2;
+	channel->gro_list = NULL;
 
 	return spent;
 }
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 961b92979640..72addac7a84a 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -502,6 +502,7 @@ struct efx_channel {
 	unsigned int rx_pkt_index;
 
 	struct list_head *rx_list;
+	struct list_head *gro_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 396ff01298cd..0534a54048c6 100644
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -453,9 +453,19 @@ efx_rx_packet_gro(struct efx_channel *channel, struct efx_rx_buffer *rx_buf,
 
 	skb_record_rx_queue(skb, channel->rx_queue.core_index);
 
-	gro_result = napi_gro_frags(napi);
-	if (gro_result != GRO_DROP)
-		channel->irq_mod_score += 2;
+	/* Pass the packet up */
+	if (channel->gro_list != NULL) {
+		/* Clear napi->skb and prepare skb for GRO */
+		skb = napi_frags_skb(napi);
+		if (skb)
+			/* Add to list, will pass up later */
+			list_add_tail(&skb->list, channel->gro_list);
+	} else {
+		/* No list, so pass it up now */
+		gro_result = napi_gro_frags(napi);
+		if (gro_result != GRO_DROP)
+			channel->irq_mod_score += 2;
+	}
 }
 
 /* Allocate and construct an SKB around page fragments */