From: Eric Dumazet <dada1@cosmosbay.com>
Date: Sat, 21 Mar 2009 20:42:55 +0000 (-0700)
Subject: net: remove useless prefetch() call
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ed734a97c6a81b644bd648afd7a337deb0ccd7e5;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git

net: remove useless prefetch() call

There is no gain using prefetch() in dev_hard_start_xmit(), since
we already had to read ops->ndo_select_queue pointer in dev_pick_tx(),
and both pointers are probably located in the same cache line.

This prefetch call slows down fast path because of a stall in address
computation.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/core/dev.c b/net/core/dev.c
index fdb9973b82a6..052dd478d3e1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1670,7 +1670,6 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 	const struct net_device_ops *ops = dev->netdev_ops;
 	int rc;
 
-	prefetch(&dev->netdev_ops->ndo_start_xmit);
 	if (likely(!skb->next)) {
 		if (!list_empty(&ptype_all))
 			dev_queue_xmit_nit(skb, dev);