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[UDP]: UDP can use sk_hash to speedup lookups

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In a prior patch, I introduced a sk_hash field (__sk_common.skc_hash)  to let
tcp lookups use one cache line per unmatched entry instead of two.

We can also use sk_hash to speedup UDP part as well. We store in sk_hash the
hnum value, and use sk->sk_hash (same cache line than 'next' pointer),
instead of inet->num (different cache line)

Note : We still have a false sharing problem for SMP machines, because
sock_hold(sock) dirties the cache line containing the 'next' pointer. Not
counting the udp_hash_lock rwlock. (did someone mentioned RCU ? :) )

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2007-02-09 15:44:52 -08:00
committed by David S. Miller
parent 4768fbcbcf
commit 95f30b336b
2 changed files with 7 additions and 6 deletions
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4
net/ipv6/udp.c
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@ -71,7 +71,7 @@ static struct sock *__udp6_lib_lookup(struct in6_addr *saddr, __be16 sport,
sk_for_each(sk, node, &udptable[hnum & (UDP_HTABLE_SIZE - 1)]) {
struct inet_sock *inet = inet_sk(sk);
if (inet->num == hnum && sk->sk_family == PF_INET6) {
if (sk->sk_hash == hnum && sk->sk_family == PF_INET6) {
struct ipv6_pinfo *np = inet6_sk(sk);
int score = 0;
if (inet->dport) {
@ -309,7 +309,7 @@ static struct sock *udp_v6_mcast_next(struct sock *sk,
sk_for_each_from(s, node) {
struct inet_sock *inet = inet_sk(s);
if (inet->num == num && s->sk_family == PF_INET6) {
if (s->sk_hash == num && s->sk_family == PF_INET6) {
struct ipv6_pinfo *np = inet6_sk(s);
if (inet->dport) {
if (inet->dport != rmt_port)