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author | Eric Dumazet <dada1@cosmosbay.com> | 2005-10-03 14:13:38 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2005-10-03 14:13:38 -0700 |
commit | 81c3d5470ecc70564eb9209946730fe2be93ad06 (patch) | |
tree | 1efa553c305a6453769dacfaf580bc6ccf146d82 /include/net/inet_timewait_sock.h | |
parent | 399de50bbbb2501a6db43daaa8a2dafbc9bcfe0c (diff) | |
download | kernel_samsung_espresso10-81c3d5470ecc70564eb9209946730fe2be93ad06.zip kernel_samsung_espresso10-81c3d5470ecc70564eb9209946730fe2be93ad06.tar.gz kernel_samsung_espresso10-81c3d5470ecc70564eb9209946730fe2be93ad06.tar.bz2 |
[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>
Diffstat (limited to 'include/net/inet_timewait_sock.h')
-rw-r--r-- | include/net/inet_timewait_sock.h | 2 |
1 files changed, 1 insertions, 1 deletions
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 @@ struct inet_timewait_sock { #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 @@ struct inet_timewait_sock { /* 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; |