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net: Implement simple sw TX hashing.

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It just xor hashes over IPv4/IPv6 addresses and ports of transport.

The only assumption it makes is that skb_network_header() is set
correctly.

With bug fixes from Eric Dumazet.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2008-07-15 03:47:03 -07:00
parent 51cb6db0f5
commit 8f0f2223cc
1 changed files with 52 additions and 0 deletions
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52
net/core/dev.c
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@@ -121,6 +121,9 @@
#include <linux/ctype.h> #include <linux/ctype.h>
#include <linux/if_arp.h> #include <linux/if_arp.h>
#include <linux/if_vlan.h> #include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include "net-sysfs.h" #include "net-sysfs.h"
@@ -1665,6 +1668,53 @@ out_kfree_skb:
* --BLG * --BLG
*/ */
static u16 simple_tx_hash(struct net_device *dev, struct sk_buff *skb)
{
u32 *addr, *ports, hash, ihl;
u8 ip_proto;
int alen;
switch (skb->protocol) {
case __constant_htons(ETH_P_IP):
ip_proto = ip_hdr(skb)->protocol;
addr = &ip_hdr(skb)->saddr;
ihl = ip_hdr(skb)->ihl;
alen = 2;
break;
case __constant_htons(ETH_P_IPV6):
ip_proto = ipv6_hdr(skb)->nexthdr;
addr = &ipv6_hdr(skb)->saddr.s6_addr32[0];
ihl = (40 >> 2);
alen = 8;
break;
default:
return 0;
}
ports = (u32 *) (skb_network_header(skb) + (ihl * 4));
hash = 0;
while (alen--)
hash ^= *addr++;
switch (ip_proto) {
case IPPROTO_TCP:
case IPPROTO_UDP:
case IPPROTO_DCCP:
case IPPROTO_ESP:
case IPPROTO_AH:
case IPPROTO_SCTP:
case IPPROTO_UDPLITE:
hash ^= *ports;
break;
default:
break;
}
return hash % dev->real_num_tx_queues;
}
static struct netdev_queue *dev_pick_tx(struct net_device *dev, static struct netdev_queue *dev_pick_tx(struct net_device *dev,
struct sk_buff *skb) struct sk_buff *skb)
{ {
@@ -1672,6 +1722,8 @@ static struct netdev_queue *dev_pick_tx(struct net_device *dev,
if (dev->select_queue) if (dev->select_queue)
queue_index = dev->select_queue(dev, skb); queue_index = dev->select_queue(dev, skb);
else if (dev->real_num_tx_queues > 1)
queue_index = simple_tx_hash(dev, skb);
skb_set_queue_mapping(skb, queue_index); skb_set_queue_mapping(skb, queue_index);
return netdev_get_tx_queue(dev, queue_index); return netdev_get_tx_queue(dev, queue_index);