: Shuffle conntrack structure for better cacheline behavior

[email protected], 2004-09-18 23:44:40+02:00, [email protected]
[NETFILTER]: Shuffle conntrack structure for better cacheline behavior

Every time we walk the conntrack hashtable list, we hit the same cacheline that is dirtied by the use of the conntrack entry. Shuffling these entries to the end should help this (sizeof(struct ip_conntrack)) > cacheline size).

# This is a BitKeeper generated diff -Nru style patch. #
# ChangeSet
# 2004/09/18 23:44:40+02:00 [email protected]
# [NETFILTER]: Shuffle conntrack structure for better cacheline behavior
#

#   Every time we walk the conntrack hashtable list, we hit the same
#   cacheline that is dirtied by the use of the conntrack
#   entry. Shuffling these entries to the end should help this
#   (sizeof(struct ip_conntrack)) > cacheline size).

#
# Signed-off-by: Rusty Russell <[email protected]>
# Signed-off-by: Patrick McHardy <[email protected]>
#

# include/linux/netfilter_ipv4/ip_conntrack.h
#   2004/09/18 23:44:13+02:00 [email protected] +3 -3
#   [NETFILTER]: Shuffle conntrack structure for better cacheline behavior
#   
#   Every time we walk the conntrack hashtable list, we hit the same
#   cacheline that is dirtied by the use of the conntrack
#   entry. Shuffling these entries to the end should help this
#   (sizeof(struct ip_conntrack)) > cacheline size).
#   
#   Signed-off-by: Rusty Russell <[email protected]>
#   Signed-off-by: Patrick McHardy <[email protected]>
# 
diff -Nru a/include/linux/netfilter_ipv4/ip_conntrack.h b/include/linux/netfilter_ipv4/ip_conntrack.h
--- a/include/linux/netfilter_ipv4/ip_conntrack.h	2004-09-20 11:57:16 +02:00
+++ b/include/linux/netfilter_ipv4/ip_conntrack.h	2004-09-20 11:57:16 +02:00
@@ -172,9 +172,6 @@
            plus 1 for any connection(s) we are `master' for */
 	struct nf_conntrack ct_general;

- /* These are my tuples; original and reply */
- struct ip_conntrack_tuple_hash tuplehash[IP_CT_DIR_MAX];
-
/* Have we seen traffic both ways yet? (bitset) */ unsigned long status;

@@ -220,6 +217,9 @@
} nat;
#endif /* CONFIG_IP_NF_NAT_NEEDED */

+ /* Traversed often, so hopefully in different cacheline to top */
+ /* These are my tuples; original and reply */
+ struct ip_conntrack_tuple_hash tuplehash[IP_CT_DIR_MAX];
};

/* get master conntrack via master expectation */