diff options
author | Eric Dumazet <dada1@cosmosbay.com> | 2005-10-03 21:13:38 (GMT) |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2005-10-03 21:13:38 (GMT) |
commit | 81c3d5470ecc70564eb9209946730fe2be93ad06 (patch) | |
tree | 1efa553c305a6453769dacfaf580bc6ccf146d82 /include/net/inet6_hashtables.h | |
parent | 399de50bbbb2501a6db43daaa8a2dafbc9bcfe0c (diff) | |
download | linux-fsl-qoriq-81c3d5470ecc70564eb9209946730fe2be93ad06.tar.xz |
[INET]: speedup inet (tcp/dccp) lookups
Arnaldo and I agreed it could be applied now, because I have other
pending patches depending on this one (Thank you Arnaldo)
(The other important patch moves skc_refcnt in a separate cache line,
so that the SMP/NUMA performance doesnt suffer from cache line ping pongs)
1) First some performance data :
--------------------------------
tcp_v4_rcv() wastes a *lot* of time in __inet_lookup_established()
The most time critical code is :
sk_for_each(sk, node, &head->chain) {
if (INET_MATCH(sk, acookie, saddr, daddr, ports, dif))
goto hit; /* You sunk my battleship! */
}
The sk_for_each() does use prefetch() hints but only the begining of
"struct sock" is prefetched.
As INET_MATCH first comparison uses inet_sk(__sk)->daddr, wich is far
away from the begining of "struct sock", it has to bring into CPU
cache cold cache line. Each iteration has to use at least 2 cache
lines.
This can be problematic if some chains are very long.
2) The goal
-----------
The idea I had is to change things so that INET_MATCH() may return
FALSE in 99% of cases only using the data already in the CPU cache,
using one cache line per iteration.
3) Description of the patch
---------------------------
Adds a new 'unsigned int skc_hash' field in 'struct sock_common',
filling a 32 bits hole on 64 bits platform.
struct sock_common {
unsigned short skc_family;
volatile unsigned char skc_state;
unsigned char skc_reuse;
int skc_bound_dev_if;
struct hlist_node skc_node;
struct hlist_node skc_bind_node;
atomic_t skc_refcnt;
+ unsigned int skc_hash;
struct proto *skc_prot;
};
Store in this 32 bits field the full hash, not masked by (ehash_size -
1) Using this full hash as the first comparison done in INET_MATCH
permits us immediatly skip the element without touching a second cache
line in case of a miss.
Suppress the sk_hashent/tw_hashent fields since skc_hash (aliased to
sk_hash and tw_hash) already contains the slot number if we mask with
(ehash_size - 1)
File include/net/inet_hashtables.h
64 bits platforms :
#define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
(((__sk)->sk_hash == (__hash))
((*((__u64 *)&(inet_sk(__sk)->daddr)))== (__cookie)) && \
((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \
(!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
32bits platforms:
#define TCP_IPV4_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\
(((__sk)->sk_hash == (__hash)) && \
(inet_sk(__sk)->daddr == (__saddr)) && \
(inet_sk(__sk)->rcv_saddr == (__daddr)) && \
(!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
- Adds a prefetch(head->chain.first) in
__inet_lookup_established()/__tcp_v4_check_established() and
__inet6_lookup_established()/__tcp_v6_check_established() and
__dccp_v4_check_established() to bring into cache the first element of the
list, before the {read|write}_lock(&head->lock);
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/inet6_hashtables.h')
-rw-r--r-- | include/net/inet6_hashtables.h | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index 03df3b1..5a2beed 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -26,19 +26,18 @@ struct inet_hashinfo; /* I have no idea if this is a good hash for v6 or not. -DaveM */ -static inline int inet6_ehashfn(const struct in6_addr *laddr, const u16 lport, - const struct in6_addr *faddr, const u16 fport, - const int ehash_size) +static inline unsigned int inet6_ehashfn(const struct in6_addr *laddr, const u16 lport, + const struct in6_addr *faddr, const u16 fport) { - int hashent = (lport ^ fport); + unsigned int hashent = (lport ^ fport); hashent ^= (laddr->s6_addr32[3] ^ faddr->s6_addr32[3]); hashent ^= hashent >> 16; hashent ^= hashent >> 8; - return (hashent & (ehash_size - 1)); + return hashent; } -static inline int inet6_sk_ehashfn(const struct sock *sk, const int ehash_size) +static inline int inet6_sk_ehashfn(const struct sock *sk) { const struct inet_sock *inet = inet_sk(sk); const struct ipv6_pinfo *np = inet6_sk(sk); @@ -46,7 +45,7 @@ static inline int inet6_sk_ehashfn(const struct sock *sk, const int ehash_size) const struct in6_addr *faddr = &np->daddr; const __u16 lport = inet->num; const __u16 fport = inet->dport; - return inet6_ehashfn(laddr, lport, faddr, fport, ehash_size); + return inet6_ehashfn(laddr, lport, faddr, fport); } /* @@ -69,14 +68,14 @@ static inline struct sock * /* Optimize here for direct hit, only listening connections can * have wildcards anyways. */ - const int hash = inet6_ehashfn(daddr, hnum, saddr, sport, - hashinfo->ehash_size); - struct inet_ehash_bucket *head = &hashinfo->ehash[hash]; + unsigned int hash = inet6_ehashfn(daddr, hnum, saddr, sport); + struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash); + prefetch(head->chain.first); read_lock(&head->lock); sk_for_each(sk, node, &head->chain) { /* For IPV6 do the cheaper port and family tests first. */ - if (INET6_MATCH(sk, saddr, daddr, ports, dif)) + if (INET6_MATCH(sk, hash, saddr, daddr, ports, dif)) goto hit; /* You sunk my battleship! */ } /* Must check for a TIME_WAIT'er before going to listener hash. */ |