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authorKrishna Kumar <krkumar2@in.ibm.com>2009-02-18 20:55:02 -0500
committerDavid S. Miller <davem@davemloft.net>2009-02-18 20:55:02 -0500
commite88721f87d8caa679e62d6004a9a5661f1ac7b0e (patch)
tree4e5ad54f7445631ac2ec5750dbe245e6c26a140c /net/core
parent38bb045d493cc166920834087acd934dedc1b5d5 (diff)
net: Optimize skb_tx_hash() by eliminating a comparison
Optimize skb_tx_hash() by eliminating a comparison that executes for every packet. skb_tx_hashrnd initialization is moved to a later part of the startup sequence, namely after the "random" driver is initialized. Rebooted the system three times and verified that the code generates different random numbers each time. Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index d393fc997cd9..5493394118fb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1745,17 +1745,11 @@ out_kfree_skb:
1745} 1745}
1746 1746
1747static u32 skb_tx_hashrnd; 1747static u32 skb_tx_hashrnd;
1748static int skb_tx_hashrnd_initialized = 0;
1749 1748
1750static u16 skb_tx_hash(struct net_device *dev, struct sk_buff *skb) 1749static u16 skb_tx_hash(struct net_device *dev, struct sk_buff *skb)
1751{ 1750{
1752 u32 hash; 1751 u32 hash;
1753 1752
1754 if (unlikely(!skb_tx_hashrnd_initialized)) {
1755 get_random_bytes(&skb_tx_hashrnd, 4);
1756 skb_tx_hashrnd_initialized = 1;
1757 }
1758
1759 if (skb_rx_queue_recorded(skb)) { 1753 if (skb_rx_queue_recorded(skb)) {
1760 hash = skb_get_rx_queue(skb); 1754 hash = skb_get_rx_queue(skb);
1761 } else if (skb->sk && skb->sk->sk_hash) { 1755 } else if (skb->sk && skb->sk->sk_hash) {
@@ -5291,6 +5285,14 @@ out:
5291 5285
5292subsys_initcall(net_dev_init); 5286subsys_initcall(net_dev_init);
5293 5287
5288static int __init initialize_hashrnd(void)
5289{
5290 get_random_bytes(&skb_tx_hashrnd, sizeof(skb_tx_hashrnd));
5291 return 0;
5292}
5293
5294late_initcall_sync(initialize_hashrnd);
5295
5294EXPORT_SYMBOL(__dev_get_by_index); 5296EXPORT_SYMBOL(__dev_get_by_index);
5295EXPORT_SYMBOL(__dev_get_by_name); 5297EXPORT_SYMBOL(__dev_get_by_name);
5296EXPORT_SYMBOL(__dev_remove_pack); 5298EXPORT_SYMBOL(__dev_remove_pack);