netdev - [PATCH] sh_eth: Optimization for RX excess judgement

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Date:	Thu, 13 Nov 2014 16:00:31 +0900
From:	Yoshihiro Kaneko <ykaneko0929@...il.com>
To:	netdev@...r.kernel.org
Cc:	"David S. Miller" <davem@...emloft.net>,
	Simon Horman <horms@...ge.net.au>,
	Magnus Damm <magnus.damm@...il.com>, linux-sh@...r.kernel.org
Subject: [PATCH] sh_eth: Optimization for RX excess judgement

From: Mitsuhiro Kimura <mitsuhiro.kimura.kc@...esas.com>

Both of 'boguscnt' and 'quota' have nearly meaning as the condition of
the reception loop.
In order to cut down redundant processing, this patch changes excess judgement.

Signed-off-by: Mitsuhiro Kimura <mitsuhiro.kimura.kc@...esas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@...il.com>
---

This patch is based on net tree.

 drivers/net/ethernet/renesas/sh_eth.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 60e9c2c..7d46326 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1394,10 +1394,15 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
 
 	int entry = mdp->cur_rx % mdp->num_rx_ring;
 	int boguscnt = (mdp->dirty_rx + mdp->num_rx_ring) - mdp->cur_rx;
+	int limit = boguscnt;
 	struct sk_buff *skb;
 	u16 pkt_len = 0;
 	u32 desc_status;
 
+	if (quota) {
+		boguscnt = min(boguscnt, *quota);
+		limit = boguscnt;
+	}
 	rxdesc = &mdp->rx_ring[entry];
 	while (!(rxdesc->status & cpu_to_edmac(mdp, RD_RACT))) {
 		desc_status = edmac_to_cpu(mdp, rxdesc->status);
@@ -1406,11 +1411,6 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
 		if (--boguscnt < 0)
 			break;
 
-		if (*quota <= 0)
-			break;
-
-		(*quota)--;
-
 		if (!(desc_status & RDFEND))
 			ndev->stats.rx_length_errors++;
 
@@ -1501,7 +1501,10 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
 		sh_eth_write(ndev, EDRRR_R, EDRRR);
 	}
 
-	return *quota <= 0;
+	if (quota)
+		*quota -= limit - (++boguscnt);
+
+	return (boguscnt <= 0);
 }
 
 static void sh_eth_rcv_snd_disable(struct net_device *ndev)
-- 
1.9.1

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