81c3d5470e
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>
220 lines
6.4 KiB
C
220 lines
6.4 KiB
C
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Definitions for a generic INET TIMEWAIT sock
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*
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* From code originally in net/tcp.h
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _INET_TIMEWAIT_SOCK_
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#define _INET_TIMEWAIT_SOCK_
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#include <linux/config.h>
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#include <linux/ip.h>
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#include <linux/list.h>
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#include <linux/timer.h>
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#include <linux/types.h>
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#include <linux/workqueue.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <asm/atomic.h>
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struct inet_hashinfo;
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#define INET_TWDR_RECYCLE_SLOTS_LOG 5
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#define INET_TWDR_RECYCLE_SLOTS (1 << INET_TWDR_RECYCLE_SLOTS_LOG)
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/*
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* If time > 4sec, it is "slow" path, no recycling is required,
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* so that we select tick to get range about 4 seconds.
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*/
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#if HZ <= 16 || HZ > 4096
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# error Unsupported: HZ <= 16 or HZ > 4096
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#elif HZ <= 32
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# define INET_TWDR_RECYCLE_TICK (5 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#elif HZ <= 64
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# define INET_TWDR_RECYCLE_TICK (6 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#elif HZ <= 128
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# define INET_TWDR_RECYCLE_TICK (7 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#elif HZ <= 256
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# define INET_TWDR_RECYCLE_TICK (8 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#elif HZ <= 512
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# define INET_TWDR_RECYCLE_TICK (9 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#elif HZ <= 1024
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# define INET_TWDR_RECYCLE_TICK (10 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#elif HZ <= 2048
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# define INET_TWDR_RECYCLE_TICK (11 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#else
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# define INET_TWDR_RECYCLE_TICK (12 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
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#endif
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/* TIME_WAIT reaping mechanism. */
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#define INET_TWDR_TWKILL_SLOTS 8 /* Please keep this a power of 2. */
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#define INET_TWDR_TWKILL_QUOTA 100
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struct inet_timewait_death_row {
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/* Short-time timewait calendar */
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int twcal_hand;
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int twcal_jiffie;
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struct timer_list twcal_timer;
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struct hlist_head twcal_row[INET_TWDR_RECYCLE_SLOTS];
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spinlock_t death_lock;
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int tw_count;
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int period;
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u32 thread_slots;
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struct work_struct twkill_work;
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struct timer_list tw_timer;
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int slot;
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struct hlist_head cells[INET_TWDR_TWKILL_SLOTS];
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struct inet_hashinfo *hashinfo;
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int sysctl_tw_recycle;
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int sysctl_max_tw_buckets;
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};
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extern void inet_twdr_hangman(unsigned long data);
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extern void inet_twdr_twkill_work(void *data);
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extern void inet_twdr_twcal_tick(unsigned long data);
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#if (BITS_PER_LONG == 64)
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#define INET_TIMEWAIT_ADDRCMP_ALIGN_BYTES 8
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#else
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#define INET_TIMEWAIT_ADDRCMP_ALIGN_BYTES 4
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#endif
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struct inet_bind_bucket;
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/*
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* This is a TIME_WAIT sock. It works around the memory consumption
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* problems of sockets in such a state on heavily loaded servers, but
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* without violating the protocol specification.
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*/
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struct inet_timewait_sock {
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/*
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* Now struct sock also uses sock_common, so please just
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* don't add nothing before this first member (__tw_common) --acme
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*/
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struct sock_common __tw_common;
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#define tw_family __tw_common.skc_family
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#define tw_state __tw_common.skc_state
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#define tw_reuse __tw_common.skc_reuse
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#define tw_bound_dev_if __tw_common.skc_bound_dev_if
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#define tw_node __tw_common.skc_node
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#define tw_bind_node __tw_common.skc_bind_node
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#define tw_refcnt __tw_common.skc_refcnt
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#define tw_hash __tw_common.skc_hash
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#define tw_prot __tw_common.skc_prot
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volatile unsigned char tw_substate;
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/* 3 bits hole, try to pack */
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unsigned char tw_rcv_wscale;
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/* Socket demultiplex comparisons on incoming packets. */
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/* these five are in inet_sock */
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__u16 tw_sport;
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__u32 tw_daddr __attribute__((aligned(INET_TIMEWAIT_ADDRCMP_ALIGN_BYTES)));
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__u32 tw_rcv_saddr;
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__u16 tw_dport;
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__u16 tw_num;
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/* And these are ours. */
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__u8 tw_ipv6only:1;
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/* 31 bits hole, try to pack */
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int tw_timeout;
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unsigned long tw_ttd;
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struct inet_bind_bucket *tw_tb;
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struct hlist_node tw_death_node;
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};
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static inline void inet_twsk_add_node(struct inet_timewait_sock *tw,
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struct hlist_head *list)
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{
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hlist_add_head(&tw->tw_node, list);
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}
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static inline void inet_twsk_add_bind_node(struct inet_timewait_sock *tw,
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struct hlist_head *list)
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{
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hlist_add_head(&tw->tw_bind_node, list);
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}
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static inline int inet_twsk_dead_hashed(const struct inet_timewait_sock *tw)
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{
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return tw->tw_death_node.pprev != NULL;
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}
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static inline void inet_twsk_dead_node_init(struct inet_timewait_sock *tw)
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{
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tw->tw_death_node.pprev = NULL;
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}
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static inline void __inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
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{
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__hlist_del(&tw->tw_death_node);
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inet_twsk_dead_node_init(tw);
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}
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static inline int inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
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{
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if (inet_twsk_dead_hashed(tw)) {
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__inet_twsk_del_dead_node(tw);
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return 1;
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}
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return 0;
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}
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#define inet_twsk_for_each(tw, node, head) \
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hlist_for_each_entry(tw, node, head, tw_node)
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#define inet_twsk_for_each_inmate(tw, node, jail) \
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hlist_for_each_entry(tw, node, jail, tw_death_node)
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#define inet_twsk_for_each_inmate_safe(tw, node, safe, jail) \
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hlist_for_each_entry_safe(tw, node, safe, jail, tw_death_node)
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static inline struct inet_timewait_sock *inet_twsk(const struct sock *sk)
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{
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return (struct inet_timewait_sock *)sk;
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}
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static inline u32 inet_rcv_saddr(const struct sock *sk)
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{
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return likely(sk->sk_state != TCP_TIME_WAIT) ?
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inet_sk(sk)->rcv_saddr : inet_twsk(sk)->tw_rcv_saddr;
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}
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static inline void inet_twsk_put(struct inet_timewait_sock *tw)
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{
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if (atomic_dec_and_test(&tw->tw_refcnt)) {
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#ifdef SOCK_REFCNT_DEBUG
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printk(KERN_DEBUG "%s timewait_sock %p released\n",
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tw->tw_prot->name, tw);
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#endif
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kmem_cache_free(tw->tw_prot->twsk_slab, tw);
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}
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}
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extern struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
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const int state);
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extern void __inet_twsk_kill(struct inet_timewait_sock *tw,
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struct inet_hashinfo *hashinfo);
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extern void __inet_twsk_hashdance(struct inet_timewait_sock *tw,
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struct sock *sk,
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struct inet_hashinfo *hashinfo);
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extern void inet_twsk_schedule(struct inet_timewait_sock *tw,
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struct inet_timewait_death_row *twdr,
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const int timeo, const int timewait_len);
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extern void inet_twsk_deschedule(struct inet_timewait_sock *tw,
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struct inet_timewait_death_row *twdr);
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#endif /* _INET_TIMEWAIT_SOCK_ */
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