kernel-ark/include/linux/tc_ematch/tc_em_meta.h
Eric Dumazet 81c3d5470e [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>
2005-10-03 14:13:38 -07:00

95 lines
1.9 KiB
C

#ifndef __LINUX_TC_EM_META_H
#define __LINUX_TC_EM_META_H
#include <linux/pkt_cls.h>
enum
{
TCA_EM_META_UNSPEC,
TCA_EM_META_HDR,
TCA_EM_META_LVALUE,
TCA_EM_META_RVALUE,
__TCA_EM_META_MAX
};
#define TCA_EM_META_MAX (__TCA_EM_META_MAX - 1)
struct tcf_meta_val
{
__u16 kind;
__u8 shift;
__u8 op;
};
#define TCF_META_TYPE_MASK (0xf << 12)
#define TCF_META_TYPE(kind) (((kind) & TCF_META_TYPE_MASK) >> 12)
#define TCF_META_ID_MASK 0x7ff
#define TCF_META_ID(kind) ((kind) & TCF_META_ID_MASK)
enum
{
TCF_META_TYPE_VAR,
TCF_META_TYPE_INT,
__TCF_META_TYPE_MAX
};
#define TCF_META_TYPE_MAX (__TCF_META_TYPE_MAX - 1)
enum
{
TCF_META_ID_VALUE,
TCF_META_ID_RANDOM,
TCF_META_ID_LOADAVG_0,
TCF_META_ID_LOADAVG_1,
TCF_META_ID_LOADAVG_2,
TCF_META_ID_DEV,
TCF_META_ID_PRIORITY,
TCF_META_ID_PROTOCOL,
TCF_META_ID_PKTTYPE,
TCF_META_ID_PKTLEN,
TCF_META_ID_DATALEN,
TCF_META_ID_MACLEN,
TCF_META_ID_NFMARK,
TCF_META_ID_TCINDEX,
TCF_META_ID_RTCLASSID,
TCF_META_ID_RTIIF,
TCF_META_ID_SK_FAMILY,
TCF_META_ID_SK_STATE,
TCF_META_ID_SK_REUSE,
TCF_META_ID_SK_BOUND_IF,
TCF_META_ID_SK_REFCNT,
TCF_META_ID_SK_SHUTDOWN,
TCF_META_ID_SK_PROTO,
TCF_META_ID_SK_TYPE,
TCF_META_ID_SK_RCVBUF,
TCF_META_ID_SK_RMEM_ALLOC,
TCF_META_ID_SK_WMEM_ALLOC,
TCF_META_ID_SK_OMEM_ALLOC,
TCF_META_ID_SK_WMEM_QUEUED,
TCF_META_ID_SK_RCV_QLEN,
TCF_META_ID_SK_SND_QLEN,
TCF_META_ID_SK_ERR_QLEN,
TCF_META_ID_SK_FORWARD_ALLOCS,
TCF_META_ID_SK_SNDBUF,
TCF_META_ID_SK_ALLOCS,
TCF_META_ID_SK_ROUTE_CAPS,
TCF_META_ID_SK_HASH,
TCF_META_ID_SK_LINGERTIME,
TCF_META_ID_SK_ACK_BACKLOG,
TCF_META_ID_SK_MAX_ACK_BACKLOG,
TCF_META_ID_SK_PRIO,
TCF_META_ID_SK_RCVLOWAT,
TCF_META_ID_SK_RCVTIMEO,
TCF_META_ID_SK_SNDTIMEO,
TCF_META_ID_SK_SENDMSG_OFF,
TCF_META_ID_SK_WRITE_PENDING,
__TCF_META_ID_MAX
};
#define TCF_META_ID_MAX (__TCF_META_ID_MAX - 1)
struct tcf_meta_hdr
{
struct tcf_meta_val left;
struct tcf_meta_val right;
};
#endif