linux-kernel - [RFC PATCH net-next v2 2/7] net: ravb: Count packets instead of descriptors in RX path

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Message-Id: <20240206091909.3191-3-paul.barker.ct@bp.renesas.com>
Date: Tue,  6 Feb 2024 09:19:04 +0000
From: Paul Barker <paul.barker.ct@...renesas.com>
To: Sergey Shtylyov <s.shtylyov@....ru>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: Paul Barker <paul.barker.ct@...renesas.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	netdev@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH net-next v2 2/7] net: ravb: Count packets instead of descriptors in RX path

The units of "work done" in the RX path should be packets instead of
descriptors, as large packets can be spread over multiple descriptors.

Signed-off-by: Paul Barker <paul.barker.ct@...renesas.com>
---
 drivers/net/ethernet/renesas/ravb_main.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index b18026575a2d..20193944c143 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -830,6 +830,7 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
 	struct ravb_rx_desc *desc;
 	struct sk_buff *skb;
 	dma_addr_t dma_addr;
+	int rx_packets = 0;
 	u8  desc_status;
 	u16 pkt_len;
 	u8  die_dt;
@@ -841,9 +842,8 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
 	limit = priv->dirty_rx[q] + priv->num_rx_ring[q] - priv->cur_rx[q];
 	stats = &priv->stats[q];
 
-	limit = min(limit, budget);
 	desc = &priv->gbeth_rx_ring[entry];
-	for (i = 0; i < limit && desc->die_dt != DT_FEMPTY; i++) {
+	for (i = 0; i < limit && rx_packets < budget && desc->die_dt != DT_FEMPTY; i++) {
 		/* Descriptor type must be checked before all other reads */
 		dma_rmb();
 		desc_status = desc->msc;
@@ -876,7 +876,7 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
 				if (ndev->features & NETIF_F_RXCSUM)
 					ravb_rx_csum_gbeth(skb);
 				napi_gro_receive(&priv->napi[q], skb);
-				stats->rx_packets++;
+				rx_packets++;
 				stats->rx_bytes += pkt_len;
 				break;
 			case DT_FSTART:
@@ -906,7 +906,7 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
 					ravb_rx_csum_gbeth(skb);
 				napi_gro_receive(&priv->napi[q],
 						 priv->rx_1st_skb);
-				stats->rx_packets++;
+				rx_packets++;
 				stats->rx_bytes += pkt_len;
 				break;
 			}
@@ -945,7 +945,8 @@ static int ravb_rx_gbeth(struct net_device *ndev, int budget, int q)
 		desc->die_dt = DT_FEMPTY;
 	}
 
-	return i;
+	stats->rx_packets += rx_packets;
+	return rx_packets;
 }
 
 /* Packet receive function for Ethernet AVB */
@@ -960,14 +961,14 @@ static int ravb_rx_rcar(struct net_device *ndev, int budget, int q)
 	struct sk_buff *skb;
 	dma_addr_t dma_addr;
 	struct timespec64 ts;
+	int rx_packets = 0;
 	u8  desc_status;
 	u16 pkt_len;
 	int limit;
 	int i;
 
-	limit = min(limit, budget);
 	desc = &priv->rx_ring[q][entry];
-	for (i = 0; i < limit && desc->die_dt != DT_FEMPTY; i++) {
+	for (i = 0; i < limit && rx_packets < budget && desc->die_dt != DT_FEMPTY; i++) {
 		/* Descriptor type must be checked before all other reads */
 		dma_rmb();
 		desc_status = desc->msc;
@@ -1018,7 +1019,7 @@ static int ravb_rx_rcar(struct net_device *ndev, int budget, int q)
 			if (ndev->features & NETIF_F_RXCSUM)
 				ravb_rx_csum(skb);
 			napi_gro_receive(&priv->napi[q], skb);
-			stats->rx_packets++;
+			rx_packets++;
 			stats->rx_bytes += pkt_len;
 		}
 
@@ -1054,7 +1055,8 @@ static int ravb_rx_rcar(struct net_device *ndev, int budget, int q)
 		desc->die_dt = DT_FEMPTY;
 	}
 
-	return i;
+	stats->rx_packets += rx_packets;
+	return rx_packets;
 }
 
 /* Packet receive function for Ethernet AVB */
-- 
2.39.2