linux/net
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
..
9p 9p: fix sparse warnings 2008-10-22 18:54:47 -05:00
802 net/802/fc.c: Fix compilation warnings 2008-10-15 00:13:53 -07:00
8021q net: Use hton[sl]() instead of __constant_hton[sl]() where applicable 2008-09-20 22:20:49 -07:00
appletalk net: Rationalise email address: Network Specific Parts 2008-10-13 19:01:08 -07:00
atm net/atm/lec.c: drop code after return 2008-09-22 19:24:45 -07:00
ax25 ax25: Quick fix for making sure unaccepted sockets get destroyed. 2008-10-06 12:53:50 -07:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-10-17 08:58:52 -07:00
bridge net: Fix disjunct computation of netdev features 2008-10-23 01:11:29 -07:00
can net: Remove CONFIG_KMOD from net/ (towards removing CONFIG_KMOD entirely) 2008-10-16 15:24:51 -07:00
core net: Fix disjunct computation of netdev features 2008-10-23 01:11:29 -07:00
dccp dccp: Port redirection support for DCCP 2008-10-19 23:36:47 -07:00
decnet Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-10-17 08:58:52 -07:00
dsa dsa: fix compile bug on s390 2008-10-13 18:58:48 -07:00
econet
ethernet dsa: add support for Trailer tagging format 2008-10-08 17:24:16 -07:00
ieee80211 net/ieee80211: adjust error handling 2008-08-22 16:29:49 -04:00
ipv4 net: implement emergency route cache rebulds when gc_elasticity is exceeded 2008-10-27 17:06:14 -07:00
ipv6 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-10-20 09:06:35 -07:00
ipx
irda
iucv iucv: Fix mismerge again. 2008-09-30 03:03:35 -07:00
key af_key: fix SADB_X_SPDDELETE response 2008-10-10 14:07:03 -07:00
lapb
llc
mac80211 ath9k/mac80211: disallow fragmentation in ath9k, report to userspace 2008-10-14 21:12:37 -04:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-10-20 09:06:35 -07:00
netlabel netlabel: Add configuration support for local labeling 2008-10-10 10:16:34 -04:00
netlink net: Remove CONFIG_KMOD from net/ (towards removing CONFIG_KMOD entirely) 2008-10-16 15:24:51 -07:00
netrom netrom: Fix sock_orphan() use in nr_release 2008-10-06 12:54:57 -07:00
packet
phonet Phonet: do not reply to indication reset packets 2008-10-26 23:07:25 -07:00
rfkill net/rfkill/rfkill-input.c needs <linux/sched.h> 2008-10-14 10:23:27 -07:00
rose
rxrpc net/rxrpc: Use an IS_ERR test rather than a NULL test 2008-08-13 02:40:48 -07:00
sched Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2 2008-10-22 09:48:06 +02:00
sctp sctp: Fix to handle SHUTDOWN in SHUTDOWN_RECEIVED state 2008-10-23 01:01:18 -07:00
sunrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-10-17 08:58:52 -07:00
tipc tipc: Don't use structure names which easily globally conflict. 2008-09-02 23:38:32 -07:00
unix [PATCH] assorted path_lookup() -> kern_path() conversions 2008-10-23 05:12:52 -04:00
wanrouter
wireless wireless: fix regression caused by regulatory config option 2008-10-26 10:38:52 -07:00
x25
xfrm xfrm: MIGRATE enhancements (draft-ebalard-mext-pfkey-enhanced-migrate) 2008-10-05 13:33:42 -07:00
compat.c
Kconfig net: Distributed Switch Architecture protocol support 2008-10-08 17:15:19 -07:00
Makefile net: Distributed Switch Architecture protocol support 2008-10-08 17:15:19 -07:00
nonet.c
socket.c net: Remove CONFIG_KMOD from net/ (towards removing CONFIG_KMOD entirely) 2008-10-16 15:24:51 -07:00
sysctl_net.c
TUNABLE