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

From: Benjamin Poirier
Date: Mon Jan 06 2014 - 18:20:44 EST


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@xxxxxxxxxx>
Signed-off-by: Benjamin Poirier <bpoirier@xxxxxxx>
---
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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