Eric Dumazet 65e8354ec1 inetpeer: seqlock optimization ... David noticed : ------------------ Eric, I was profiling the non-routing-cache case and something that stuck out is the case of calling inet_getpeer() with create==0. If an entry is not found, we have to redo the lookup under a spinlock to make certain that a concurrent writer rebalancing the tree does not "hide" an existing entry from us. This makes the case of a create==0 lookup for a not-present entry really expensive. It is on the order of 600 cpu cycles on my Niagara2. I added a hack to not do the relookup under the lock when create==0 and it now costs less than 300 cycles. This is now a pretty common operation with the way we handle COW'd metrics, so I think it's definitely worth optimizing. ----------------- One solution is to use a seqlock instead of a spinlock to protect struct inet_peer_base. After a failed avl tree lookup, we can easily detect if a writer did some changes during our lookup. Taking the lock and redo the lookup is only necessary in this case. Note: Add one private rcu_deref_locked() macro to place in one spot the access to spinlock included in seqlock. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2011-03-04 14:33:59 -08:00
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9p	net: cleanup unused macros in net directory	2011-01-19 23:20:04 -08:00
802	net/802: add __rcu annotations	2010-10-25 13:09:44 -07:00
8021q	net: change netdev->features to u32	2011-01-24 15:32:47 -08:00
appletalk
atm	ipv4: Make output route lookup return rtable directly.	2011-03-02 14:31:35 -08:00
ax25	net: ax25: fix information leak to userland harder	2011-01-12 00:34:49 -08:00
batman-adv	Merge branch 'batman-adv/next' of git://git.open-mesh.org/ecsv/linux-merge	2011-02-11 21:20:27 -08:00
bluetooth	Bluetooth: Fix BT_L2CAP and BT_SCO in Kconfig	2011-02-28 14:06:53 -05:00
bridge	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
caif	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-02-08 17:19:01 -08:00
can	can: test size of struct sockaddr in sendmsg	2011-01-15 20:56:42 -08:00
ceph	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client	2011-02-21 15:01:38 -08:00
core	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
dcb	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
dccp	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
decnet	xfrm: Return dst directly from xfrm_lookup()	2011-03-02 13:27:41 -08:00
dns_resolver	DNS: Fix a NULL pointer deref when trying to read an error key [CVE-2011-1076]	2011-03-04 09:56:19 +11:00
dsa	module: fix missing semicolons in MODULE macro usage	2011-01-24 14:32:54 +10:30
econet	econet: remove compiler warnings	2011-01-27 14:15:54 -08:00
ethernet	eth: fix new kernel-doc warning	2011-01-12 19:00:40 -08:00
ieee802154	net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()	2010-12-08 10:07:24 -08:00
ipv4	inetpeer: seqlock optimization	2011-03-04 14:33:59 -08:00
ipv6	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
ipx	BKL: introduce CONFIG_BKL.	2010-10-21 15:44:13 +02:00
irda	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2010-12-26 22:37:05 -08:00
iucv	[S390] irq: have detailed statistics for interrupt types	2011-01-05 12:47:25 +01:00
key	pfkey: fix warning	2011-03-01 22:51:52 -08:00
l2tp	ipv4: Make output route lookup return rtable directly.	2011-03-02 14:31:35 -08:00
lapb	Net: lapb: Makefile: Remove deprecated kbuild goal definitions	2010-11-22 08:16:14 -08:00
llc	llc: avoid skb_clone() if there is only one handler	2011-02-28 12:28:50 -08:00
mac80211	Merge branch 'for-davem' of ssh://master.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6	2011-03-04 12:48:25 -08:00
netfilter	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
netlabel	netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms	2011-03-03 10:55:40 -08:00
netlink	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
netrom
packet	network: Allow af_packet to transmit +4 bytes for VLAN packets.	2011-02-11 21:26:32 -08:00
phonet	phonet: Protect pipe_do_remove() with appropriate ifdefs.	2011-02-25 11:23:22 -08:00
rds	net: cleanup unused macros in net directory	2011-01-19 23:20:04 -08:00
rfkill	kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT	2011-01-20 17:02:05 -08:00
rose	ROSE: AX25: finding routes simplification	2011-02-14 13:33:49 -08:00
rxrpc	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
sched	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2011-03-03 21:27:42 -08:00
sctp	ipv4: Make output route lookup return rtable directly.	2011-03-02 14:31:35 -08:00
sunrpc	net: add __rcu annotations to sk_wq and wq	2011-02-22 10:19:31 -08:00
tipc	tipc: Avoid reliable broadcast preparation for NACK messages	2011-02-23 18:05:23 -05:00
unix	net: add __rcu annotations to sk_wq and wq	2011-02-22 10:19:31 -08:00
wanrouter	net: cleanup unused macros in net directory	2011-01-19 23:20:04 -08:00
wimax
wireless	Merge branch 'for-davem' of ssh://master.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6	2011-03-04 12:48:25 -08:00
x25	x25: Do not reference freed memory.	2011-02-09 22:36:13 -08:00
xfrm	netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms	2011-03-03 10:55:40 -08:00
compat.c	net: Limit socket I/O iovec total length to INT_MAX.	2010-10-28 11:47:52 -07:00
Kconfig	net: RPS: Enable hardware acceleration of RFS	2011-01-24 14:53:01 -08:00
Makefile	net: Add batman-adv meshing protocol	2010-12-16 13:44:24 -08:00
nonet.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
socket.c	socket: suppress sparse warnings	2011-02-23 14:11:30 -08:00
sysctl_net.c
TUNABLE