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>
diff --git a/net/core/dev.c b/net/core/dev.c
index d393fc9..5493394 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1745,17 +1745,11 @@
}
static u32 skb_tx_hashrnd;
-static int skb_tx_hashrnd_initialized = 0;
static u16 skb_tx_hash(struct net_device *dev, struct sk_buff *skb)
{
u32 hash;
- if (unlikely(!skb_tx_hashrnd_initialized)) {
- get_random_bytes(&skb_tx_hashrnd, 4);
- skb_tx_hashrnd_initialized = 1;
- }
-
if (skb_rx_queue_recorded(skb)) {
hash = skb_get_rx_queue(skb);
} else if (skb->sk && skb->sk->sk_hash) {
@@ -5291,6 +5285,14 @@
subsys_initcall(net_dev_init);
+static int __init initialize_hashrnd(void)
+{
+ get_random_bytes(&skb_tx_hashrnd, sizeof(skb_tx_hashrnd));
+ return 0;
+}
+
+late_initcall_sync(initialize_hashrnd);
+
EXPORT_SYMBOL(__dev_get_by_index);
EXPORT_SYMBOL(__dev_get_by_name);
EXPORT_SYMBOL(__dev_remove_pack);