linux-kernel - [PATCH] net: Do not enable tx-nocache-copy by default

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Message-Id: <1389050419-9060-1-git-send-email-bpoirier@suse.de>
Date:	Mon,  6 Jan 2014 18:20:19 -0500
From:	Benjamin Poirier <bpoirier@...e.de>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Tom Herbert <therbert@...gle.com>
Subject: [PATCH] net: Do not enable tx-nocache-copy by default

There are many cases where this feature does not improve performance or even
reduces it. See the following discussion for example perf numbers:
http://thread.gmane.org/gmane.linux.network/298345

CC: Tom Herbert <therbert@...gle.com>
Signed-off-by: Benjamin Poirier <bpoirier@...e.de>
---
 net/core/dev.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 153ee2f..2e242583 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5783,13 +5783,8 @@ int register_netdevice(struct net_device *dev)
 	dev->features |= NETIF_F_SOFT_FEATURES;
 	dev->wanted_features = dev->features & dev->hw_features;
 
-	/* Turn on no cache copy if HW is doing checksum */
 	if (!(dev->flags & IFF_LOOPBACK)) {
 		dev->hw_features |= NETIF_F_NOCACHE_COPY;
-		if (dev->features & NETIF_F_ALL_CSUM) {
-			dev->wanted_features |= NETIF_F_NOCACHE_COPY;
-			dev->features |= NETIF_F_NOCACHE_COPY;
-		}
 	}
 
 	/* Make NETIF_F_HIGHDMA inheritable to VLAN devices.
-- 
1.8.4

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