linux/include/net/netns/ipv4.h
Neil Horman 1080d709fb net: implement emergency route cache rebulds when gc_elasticity is exceeded
This is a patch to provide on demand route cache rebuilding.  Currently, our
route cache is rebulid periodically regardless of need.  This introduced
unneeded periodic latency.  This patch offers a better approach.  Using code
provided by Eric Dumazet, we compute the standard deviation of the average hash
bucket chain length while running rt_check_expire.  Should any given chain
length grow to larger that average plus 4 standard deviations, we trigger an
emergency hash table rebuild for that net namespace.  This allows for the common
case in which chains are well behaved and do not grow unevenly to not incur any
latency at all, while those systems (which may be being maliciously attacked),
only rebuild when the attack is detected.  This patch take 2 other factors into
account:
1) chains with multiple entries that differ by attributes that do not affect the
hash value are only counted once, so as not to unduly bias system to rebuilding
if features like QOS are heavily used
2) if rebuilding crosses a certain threshold (which is adjustable via the added
sysctl in this patch), route caching is disabled entirely for that net
namespace, since constant rebuilding is less efficient that no caching at all

Tested successfully by me.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-27 17:06:14 -07:00

59 lines
1.3 KiB
C

/*
* ipv4 in net namespaces
*/
#ifndef __NETNS_IPV4_H__
#define __NETNS_IPV4_H__
#include <net/inet_frag.h>
struct ctl_table_header;
struct ipv4_devconf;
struct fib_rules_ops;
struct hlist_head;
struct sock;
struct netns_ipv4 {
#ifdef CONFIG_SYSCTL
struct ctl_table_header *forw_hdr;
struct ctl_table_header *frags_hdr;
struct ctl_table_header *ipv4_hdr;
struct ctl_table_header *route_hdr;
#endif
struct ipv4_devconf *devconf_all;
struct ipv4_devconf *devconf_dflt;
#ifdef CONFIG_IP_MULTIPLE_TABLES
struct fib_rules_ops *rules_ops;
#endif
struct hlist_head *fib_table_hash;
struct sock *fibnl;
struct sock **icmp_sk;
struct sock *tcp_sock;
struct netns_frags frags;
#ifdef CONFIG_NETFILTER
struct xt_table *iptable_filter;
struct xt_table *iptable_mangle;
struct xt_table *iptable_raw;
struct xt_table *arptable_filter;
struct xt_table *iptable_security;
struct xt_table *nat_table;
struct hlist_head *nat_bysource;
int nat_vmalloced;
#endif
int sysctl_icmp_echo_ignore_all;
int sysctl_icmp_echo_ignore_broadcasts;
int sysctl_icmp_ignore_bogus_error_responses;
int sysctl_icmp_ratelimit;
int sysctl_icmp_ratemask;
int sysctl_icmp_errors_use_inbound_ifaddr;
int sysctl_rt_cache_rebuild_count;
int current_rt_cache_rebuild_count;
struct timer_list rt_secret_timer;
atomic_t rt_genid;
};
#endif