net: optimize INET input path further

Followup of commit b178bb3dfc30 (net: reorder struct sock fields)

Optimize INET input path a bit further, by :

1) moving sk_refcnt close to sk_lock.

This reduces number of dirtied cache lines by one on 64bit arches (and
64 bytes cache line size).

2) moving inet_daddr & inet_rcv_saddr at the beginning of sk

(same cache line than hash / family / bound_dev_if / nulls_node)

This reduces number of accessed cache lines in lookups by one, and dont
increase size of inet and timewait socks.
inet and tw sockets now share same place-holder for these fields.

Before patch :

offsetof(struct sock, sk_refcnt) = 0x10
offsetof(struct sock, sk_lock) = 0x40
offsetof(struct sock, sk_receive_queue) = 0x60
offsetof(struct inet_sock, inet_daddr) = 0x270
offsetof(struct inet_sock, inet_rcv_saddr) = 0x274

After patch :

offsetof(struct sock, sk_refcnt) = 0x44
offsetof(struct sock, sk_lock) = 0x48
offsetof(struct sock, sk_receive_queue) = 0x68
offsetof(struct inet_sock, inet_daddr) = 0x0
offsetof(struct inet_sock, inet_rcv_saddr) = 0x4

compute_score() (udp or tcp) now use a single cache line per ignored
item, instead of two.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 4 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 06f5f8f482f0..25e318153f14 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -55,7 +55,6 @@ EXPORT_SYMBOL(inet_get_local_port_range);
 int inet_csk_bind_conflict(const struct sock *sk,
                            const struct inet_bind_bucket *tb)
 {
-        const __be32 sk_rcv_saddr = inet_rcv_saddr(sk);
         struct sock *sk2;
         struct hlist_node *node;
         int reuse = sk->sk_reuse;
@@ -75,9 +74,9 @@ int inet_csk_bind_conflict(const struct sock *sk,
                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
                         if (!reuse || !sk2->sk_reuse ||
                             sk2->sk_state == TCP_LISTEN) {
-                                const __be32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
-                                if (!sk2_rcv_saddr || !sk_rcv_saddr ||
-                                    sk2_rcv_saddr == sk_rcv_saddr)
+                                const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
+                                if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
+                                    sk2_rcv_saddr == sk_rcv_saddr(sk))
                                         break;
                         }
                 }