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Commit fbf8866d authored by Shawn Bohrer's avatar Shawn Bohrer Committed by David S. Miller
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net: ipv4 only populate IP_PKTINFO when needed 



The since the removal of the routing cache computing
fib_compute_spec_dst() does a fib_table lookup for each UDP multicast
packet received.  This has introduced a performance regression for some
UDP workloads.

This change skips populating the packet info for sockets that do not have
IP_PKTINFO set.

Benchmark results from a netperf UDP_RR test:
Before 89789.68 transactions/s
After  90587.62 transactions/s

Benchmark results from a fio 1 byte UDP multicast pingpong test
(Multicast one way unicast response):
Before 12.63us RTT
After  12.48us RTT

Signed-off-by: default avatarShawn Bohrer <sbohrer@rgmadvisors.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 421b3885

include/net/ip.h

+1 −1
Original line number Diff line number Diff line
@@ -459,7 +459,7 @@ int ip_options_rcv_srr(struct sk_buff *skb); 
 *	Functions provided by ip_sockglue.c

 */



void ipv4_pktinfo_prepare(struct sk_buff *skb);

void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);

void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb);

int ip_cmsg_send(struct net *net, struct msghdr *msg, struct ipcm_cookie *ipc);

int ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval,

net/ipv4/ip_sockglue.c

+3 −2
Original line number Diff line number Diff line
@@ -1052,11 +1052,12 @@ static int do_ip_setsockopt(struct sock *sk, int level, 
 * destination in skb->cb[] before dst drop.

 * This way, receiver doesnt make cache line misses to read rtable.

 */

void ipv4_pktinfo_prepare(struct sk_buff *skb)

void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)

{

	struct in_pktinfo *pktinfo = PKTINFO_SKB_CB(skb);



	if (skb_rtable(skb)) {

	if ((inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) &&

	    skb_rtable(skb)) {

		pktinfo->ipi_ifindex = inet_iif(skb);

		pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);

	} else {

net/ipv4/raw.c

+1 −1
Original line number Diff line number Diff line
@@ -299,7 +299,7 @@ static int raw_rcv_skb(struct sock *sk, struct sk_buff *skb) 
{

	/* Charge it to the socket. */



	ipv4_pktinfo_prepare(skb);

	ipv4_pktinfo_prepare(sk, skb);

	if (sock_queue_rcv_skb(sk, skb) < 0) {

		kfree_skb(skb);

		return NET_RX_DROP;

net/ipv4/udp.c

+1 −1
Original line number Diff line number Diff line
@@ -1544,7 +1544,7 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb) 


	rc = 0;



	ipv4_pktinfo_prepare(skb);

	ipv4_pktinfo_prepare(sk, skb);

	bh_lock_sock(sk);

	if (!sock_owned_by_user(sk))

		rc = __udp_queue_rcv_skb(sk, skb);