[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>
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 @@
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 @@
/* 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. */
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 646b6ea..35f49e6 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -108,7 +108,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
#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 @@
/* 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;
diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index 3b07035..4ade56e 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -112,6 +112,7 @@
#define tw_node __tw_common.skc_node
#define tw_bind_node __tw_common.skc_bind_node
#define tw_refcnt __tw_common.skc_refcnt
+#define tw_hash __tw_common.skc_hash
#define tw_prot __tw_common.skc_prot
volatile unsigned char tw_substate;
/* 3 bits hole, try to pack */
@@ -126,7 +127,6 @@
/* And these are ours. */
__u8 tw_ipv6only:1;
/* 31 bits hole, try to pack */
- int tw_hashent;
int tw_timeout;
unsigned long tw_ttd;
struct inet_bind_bucket *tw_tb;
diff --git a/include/net/sock.h b/include/net/sock.h
index 8c48fbe..b644080 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -99,6 +99,7 @@
* @skc_node: main hash linkage for various protocol lookup tables
* @skc_bind_node: bind hash linkage for various protocol lookup tables
* @skc_refcnt: reference count
+ * @skc_hash: hash value used with various protocol lookup tables
* @skc_prot: protocol handlers inside a network family
*
* This is the minimal network layer representation of sockets, the header
@@ -112,6 +113,7 @@
struct hlist_node skc_node;
struct hlist_node skc_bind_node;
atomic_t skc_refcnt;
+ unsigned int skc_hash;
struct proto *skc_prot;
};
@@ -139,7 +141,6 @@
* @sk_no_check: %SO_NO_CHECK setting, wether or not checkup packets
* @sk_route_caps: route capabilities (e.g. %NETIF_F_TSO)
* @sk_lingertime: %SO_LINGER l_linger setting
- * @sk_hashent: hash entry in several tables (e.g. inet_hashinfo.ehash)
* @sk_backlog: always used with the per-socket spinlock held
* @sk_callback_lock: used with the callbacks in the end of this struct
* @sk_error_queue: rarely used
@@ -186,6 +187,7 @@
#define sk_node __sk_common.skc_node
#define sk_bind_node __sk_common.skc_bind_node
#define sk_refcnt __sk_common.skc_refcnt
+#define sk_hash __sk_common.skc_hash
#define sk_prot __sk_common.skc_prot
unsigned char sk_shutdown : 2,
sk_no_check : 2,
@@ -208,7 +210,6 @@
unsigned int sk_allocation;
int sk_sndbuf;
int sk_route_caps;
- int sk_hashent;
unsigned long sk_flags;
unsigned long sk_lingertime;
/*