netdev: simple_tx_hash shouldn't hash inside fragments (ad55dcaf) · Commits · 戴 / test

Currently simple_tx_hash is hashing inside of udp fragments. As a result packets are getting getting sent to all queues when they shouldn't be. This causes a serious performance regression which can be seen by sending UDP frames larger than mtu on multiqueue devices. This change will make it so that fragments are hashed only as IP datagrams w/o any protocol information. Signed-off-by:

Alexander Duyck <alexander.h.duyck@intel.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/dev.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -122,6 +122,7 @@
		#include <linux/if_arp.h>
		#include <linux/if_vlan.h>
		#include <linux/ip.h>
		#include <net/ip.h>
		#include <linux/ipv6.h>
		#include <linux/in.h>
		#include <linux/jhash.h>
		@@ -1667,7 +1668,7 @@ static u16 simple_tx_hash(struct net_device dev, struct sk_buff skb)
		{
		u32 addr1, addr2, ports;
		u32 hash, ihl;
		u8 ip_proto;
		u8 ip_proto = 0;

		if (unlikely(!simple_tx_hashrnd_initialized)) {
		get_random_bytes(&simple_tx_hashrnd, 4);
		@@ -1676,6 +1677,7 @@ static u16 simple_tx_hash(struct net_device dev, struct sk_buff skb)

		switch (skb->protocol) {
		case __constant_htons(ETH_P_IP):
		if (!(ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)))
		ip_proto = ip_hdr(skb)->protocol;
		addr1 = ip_hdr(skb)->saddr;
		addr2 = ip_hdr(skb)->daddr;

Admin message