From 81c3d5470ecc70564eb9209946730fe2be93ad06 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 3 Oct 2005 14:13:38 -0700 Subject: [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 Acked-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- include/net/inet_hashtables.h | 64 +++++++++++++++++++++++++------------------ 1 file changed, 38 insertions(+), 26 deletions(-) (limited to 'include/net/inet_hashtables.h') diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 646b6ea7fe26..35f49e65e295 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -108,7 +108,7 @@ struct inet_hashinfo { struct inet_bind_hashbucket *bhash; int bhash_size; - int ehash_size; + unsigned int ehash_size; /* All sockets in TCP_LISTEN state will be in here. This is the only * table where wildcard'd TCP sockets can exist. Hash function here @@ -130,17 +130,16 @@ struct inet_hashinfo { int port_rover; }; -static inline int inet_ehashfn(const __u32 laddr, const __u16 lport, - const __u32 faddr, const __u16 fport, - const int ehash_size) +static inline unsigned int inet_ehashfn(const __u32 laddr, const __u16 lport, + const __u32 faddr, const __u16 fport) { - int h = (laddr ^ lport) ^ (faddr ^ fport); + unsigned int h = (laddr ^ lport) ^ (faddr ^ fport); h ^= h >> 16; h ^= h >> 8; - return h & (ehash_size - 1); + return h; } -static inline int inet_sk_ehashfn(const struct sock *sk, const int ehash_size) +static inline int inet_sk_ehashfn(const struct sock *sk) { const struct inet_sock *inet = inet_sk(sk); const __u32 laddr = inet->rcv_saddr; @@ -148,7 +147,14 @@ static inline int inet_sk_ehashfn(const struct sock *sk, const int ehash_size) const __u32 faddr = inet->daddr; const __u16 fport = inet->dport; - return inet_ehashfn(laddr, lport, faddr, fport, ehash_size); + return inet_ehashfn(laddr, lport, faddr, fport); +} + +static inline struct inet_ehash_bucket *inet_ehash_bucket( + struct inet_hashinfo *hashinfo, + unsigned int hash) +{ + return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)]; } extern struct inet_bind_bucket * @@ -235,9 +241,11 @@ static inline void __inet_hash(struct inet_hashinfo *hashinfo, lock = &hashinfo->lhash_lock; inet_listen_wlock(hashinfo); } else { - sk->sk_hashent = inet_sk_ehashfn(sk, hashinfo->ehash_size); - list = &hashinfo->ehash[sk->sk_hashent].chain; - lock = &hashinfo->ehash[sk->sk_hashent].lock; + struct inet_ehash_bucket *head; + sk->sk_hash = inet_sk_ehashfn(sk); + head = inet_ehash_bucket(hashinfo, sk->sk_hash); + list = &head->chain; + lock = &head->lock; write_lock(lock); } __sk_add_node(sk, list); @@ -268,9 +276,8 @@ static inline void inet_unhash(struct inet_hashinfo *hashinfo, struct sock *sk) inet_listen_wlock(hashinfo); lock = &hashinfo->lhash_lock; } else { - struct inet_ehash_bucket *head = &hashinfo->ehash[sk->sk_hashent]; - lock = &head->lock; - write_lock_bh(&head->lock); + lock = &inet_ehash_bucket(hashinfo, sk->sk_hash)->lock; + write_lock_bh(lock); } if (__sk_del_node_init(sk)) @@ -337,23 +344,27 @@ sherry_cache: #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ const __u64 __name = (((__u64)(__daddr)) << 32) | ((__u64)(__saddr)); #endif /* __BIG_ENDIAN */ -#define INET_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ - (((*((__u64 *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ +#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)))) -#define INET_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ - (((*((__u64 *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ +#define INET_TW_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ + (((__sk)->sk_hash == (__hash)) && \ + ((*((__u64 *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) #else /* 32-bit arch */ #define INET_ADDR_COOKIE(__name, __saddr, __daddr) -#define INET_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif) \ - ((inet_sk(__sk)->daddr == (__saddr)) && \ +#define INET_MATCH(__sk, __hash, __cookie, __saddr, __daddr, __ports, __dif) \ + (((__sk)->sk_hash == (__hash)) && \ + (inet_sk(__sk)->daddr == (__saddr)) && \ (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) -#define INET_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif) \ - ((inet_twsk(__sk)->tw_daddr == (__saddr)) && \ +#define INET_TW_MATCH(__sk, __hash,__cookie, __saddr, __daddr, __ports, __dif) \ + (((__sk)->sk_hash == (__hash)) && \ + (inet_twsk(__sk)->tw_daddr == (__saddr)) && \ (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) @@ -378,18 +389,19 @@ static inline struct sock * /* Optimize here for direct hit, only listening connections can * have wildcards anyways. */ - const int hash = inet_ehashfn(daddr, hnum, saddr, sport, hashinfo->ehash_size); - struct inet_ehash_bucket *head = &hashinfo->ehash[hash]; + unsigned int hash = inet_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) { - if (INET_MATCH(sk, acookie, saddr, daddr, ports, dif)) + if (INET_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) goto hit; /* You sunk my battleship! */ } /* Must check for a TIME_WAIT'er before going to listener hash. */ sk_for_each(sk, node, &(head + hashinfo->ehash_size)->chain) { - if (INET_TW_MATCH(sk, acookie, saddr, daddr, ports, dif)) + if (INET_TW_MATCH(sk, hash, acookie, saddr, daddr, ports, dif)) goto hit; } sk = NULL; -- cgit v1.2.3-55-g7522