From f86dcc5aa8c7908f2c287e7a211228df599e3e71 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 7 Oct 2009 00:37:59 +0000 Subject: udp: dynamically size hash tables at boot time UDP_HTABLE_SIZE was initialy defined to 128, which is a bit small for several setups. 4000 active UDP sockets -> 32 sockets per chain in average. An incoming frame has to lookup all sockets to find best match, so long chains hurt latency. Instead of a fixed size hash table that cant be perfect for every needs, let UDP stack choose its table size at boot time like tcp/ip route, using alloc_large_system_hash() helper Add an optional boot parameter, uhash_entries=x so that an admin can force a size between 256 and 65536 if needed, like thash_entries and rhash_entries. dmesg logs two new lines : [ 0.647039] UDP hash table entries: 512 (order: 0, 4096 bytes) [ 0.647099] UDP Lite hash table entries: 512 (order: 0, 4096 bytes) Maximal size on 64bit arches would be 65536 slots, ie 1 MBytes for non debugging spinlocks. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/udp.h | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'include/net/udp.h') diff --git a/include/net/udp.h b/include/net/udp.h index f98abd2ce709..22aa2e7eb1d7 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -54,12 +54,19 @@ struct udp_hslot { struct hlist_nulls_head head; spinlock_t lock; } __attribute__((aligned(2 * sizeof(long)))); + struct udp_table { - struct udp_hslot hash[UDP_HTABLE_SIZE]; + struct udp_hslot *hash; + unsigned int mask; + unsigned int log; }; extern struct udp_table udp_table; -extern void udp_table_init(struct udp_table *); - +extern void udp_table_init(struct udp_table *, const char *); +static inline struct udp_hslot *udp_hashslot(struct udp_table *table, + struct net *net, unsigned num) +{ + return &table->hash[udp_hashfn(net, num, table->mask)]; +} /* Note: this must match 'valbool' in sock_setsockopt */ #define UDP_CSUM_NOXMIT 1 -- cgit v1.2.3 From fdcc8aa953a1123a289791dd192090651036d593 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 8 Nov 2009 10:17:05 +0000 Subject: udp: add a counter into udp_hslot Adds a counter in udp_hslot to keep an accurate count of sockets present in chain. This will permit to upcoming UDP lookup algo to chose the shortest chain when secondary hash is added. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/udp.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/net/udp.h') diff --git a/include/net/udp.h b/include/net/udp.h index 22aa2e7eb1d7..9167281e47dc 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -50,8 +50,16 @@ struct udp_skb_cb { }; #define UDP_SKB_CB(__skb) ((struct udp_skb_cb *)((__skb)->cb)) +/** + * struct udp_hslot - UDP hash slot + * + * @head: head of list of sockets + * @count: number of sockets in 'head' list + * @lock: spinlock protecting changes to head/count + */ struct udp_hslot { struct hlist_nulls_head head; + int count; spinlock_t lock; } __attribute__((aligned(2 * sizeof(long)))); -- cgit v1.2.3 From 512615b6b843ff3ff5ad583f34c39b3f302f5f26 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 8 Nov 2009 10:17:58 +0000 Subject: udp: secondary hash on (local port, local address) Extends udp_table to contain a secondary hash table. socket anchor for this second hash is free, because UDP doesnt use skc_bind_node : We define an union to hold both skc_bind_node & a new hlist_nulls_node udp_portaddr_node udp_lib_get_port() inserts sockets into second hash chain (additional cost of one atomic op) udp_lib_unhash() deletes socket from second hash chain (additional cost of one atomic op) Note : No spinlock lockdep annotation is needed, because lock for the secondary hash chain is always get after lock for primary hash chain. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/udp.h | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'include/net/udp.h') diff --git a/include/net/udp.h b/include/net/udp.h index 9167281e47dc..af41850f742a 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -63,10 +63,19 @@ struct udp_hslot { spinlock_t lock; } __attribute__((aligned(2 * sizeof(long)))); +/** + * struct udp_table - UDP table + * + * @hash: hash table, sockets are hashed on (local port) + * @hash2: hash table, sockets are hashed on (local port, local address) + * @mask: number of slots in hash tables, minus 1 + * @log: log2(number of slots in hash table) + */ struct udp_table { struct udp_hslot *hash; - unsigned int mask; - unsigned int log; + struct udp_hslot *hash2; + unsigned int mask; + unsigned int log; }; extern struct udp_table udp_table; extern void udp_table_init(struct udp_table *, const char *); @@ -75,6 +84,15 @@ static inline struct udp_hslot *udp_hashslot(struct udp_table *table, { return &table->hash[udp_hashfn(net, num, table->mask)]; } +/* + * For secondary hash, net_hash_mix() is performed before calling + * udp_hashslot2(), this explains difference with udp_hashslot() + */ +static inline struct udp_hslot *udp_hashslot2(struct udp_table *table, + unsigned int hash) +{ + return &table->hash2[hash & table->mask]; +} /* Note: this must match 'valbool' in sock_setsockopt */ #define UDP_CSUM_NOXMIT 1 -- cgit v1.2.3 From 30fff9231fad757c061285e347b33c5149c2c2e4 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 9 Nov 2009 05:26:33 +0000 Subject: udp: bind() optimisation UDP bind() can be O(N^2) in some pathological cases. Thanks to secondary hash tables, we can make it O(N) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/udp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/net/udp.h') diff --git a/include/net/udp.h b/include/net/udp.h index af41850f742a..5348d80b25bb 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -158,7 +158,8 @@ static inline void udp_lib_close(struct sock *sk, long timeout) } extern int udp_lib_get_port(struct sock *sk, unsigned short snum, - int (*)(const struct sock*,const struct sock*)); + int (*)(const struct sock *,const struct sock *), + unsigned int hash2_nulladdr); /* net/ipv4/udp.c */ extern int udp_get_port(struct sock *sk, unsigned short snum, -- cgit v1.2.3