netdev - [PATCH v3] sh_eth: Optimization for RX excess judgement

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Message-Id: <1418127822-16904-1-git-send-email-ykaneko0929@gmail.com>
Date:	Tue,  9 Dec 2014 21:23:42 +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 v3] 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-next tree.

v3 [Yoshihiro Kaneko]
* fixes the calculation error of *quota.

v2 [Yoshihiro Kaneko]
* re-spin for net-next.
* remove unneeded check of "quota".
* remove unneeded incrementation of "boguscnt".
* drop the change of the return statement.

 drivers/net/ethernet/renesas/sh_eth.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index dbe8606..f94bbf5 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1394,10 +1394,13 @@ 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;
 	struct sk_buff *skb;
 	u16 pkt_len = 0;
 	u32 desc_status;
 
+	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 +1409,6 @@ 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++;
 
@@ -1501,6 +1499,8 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
 		sh_eth_write(ndev, EDRRR_R, EDRRR);
 	}
 
+	*quota -= limit - boguscnt - 1;
+
 	return *quota <= 0;
 }
 
-- 
1.9.1

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