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27b75c95f1
kernel_optimize_test/net/ipv4
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Eric Dumazet 27b75c95f1 net: avoid RCU for NOCACHE dst 
There is no point using RCU for dst we allocate for a very short time
(used once).

Change dst_release() to take DST_NOCACHE into account, but also change
skb_dst_set_noref() to force a refcount increment for such dst.

This is a _huge_ gain, because we dont waste memory to store xx thousand
of dsts. Instead of queueing them to RCU, we can free them instantly.

CPU caches can stay hot, re-using same memory blocks to hold temporary
dsts.

Note : remove unneeded smp_mb__before_atomic_dec(); in dst_release(),
since atomic_dec_return() implies a full memory barrier.

Stress test, 160.000.000 udp frames sent, IP route cache disabled
(DDOS).

Before:

real    0m38.091s
user    0m13.189s
sys     7m53.018s

After:

real	0m29.946s
user	0m12.157s
sys	7m40.605s

For reference, if IP route cache was enabled :

real	0m32.030s
user	0m10.521s
sys	8m15.243s

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-10-20 03:02:23 -07:00
..
netfilter Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-09-27 01:03:03 -07:00
af_inet.c net: build_ehash_secret() and rt_bind_peer() cleanups 2010-08-20 00:50:16 -07:00
ah4.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
arp.c neigh: Protect neigh->ha[] with a seqlock 2010-10-11 12:54:04 -07:00
cipso_ipv4.c net: Remove unnecessary returns from void function()s 2010-05-17 23:23:14 -07:00
datagram.c net: return operator cleanup 2010-09-23 14:33:39 -07:00
devinet.c inet: RCU changes in inetdev_by_index() 2010-10-19 03:50:48 -07:00
esp4.c
fib_frontend.c net: avoid a dev refcount in ip_mc_find_dev() 2010-10-19 03:50:47 -07:00
fib_hash.c fib_hash: RCU conversion phase 2 2010-10-17 13:53:16 -07:00
fib_lookup.h fib_hash: RCU conversion phase 2 2010-10-17 13:53:16 -07:00
fib_rules.c fib: RCU conversion of fib_lookup() 2010-10-05 20:39:38 -07:00
fib_semantics.c inet: RCU changes in inetdev_by_index() 2010-10-19 03:50:48 -07:00
fib_trie.c fib_trie: use fls() instead of open coded loop 2010-10-16 11:13:22 -07:00
gre.c gre: protocol table can be static 2010-10-03 21:50:51 -07:00
icmp.c net: simplify flags for tx timestamping 2010-08-19 00:08:30 -07:00
igmp.c inet: RCU changes in inetdev_by_index() 2010-10-19 03:50:48 -07:00
inet_connection_sock.c net/ipv4: EXPORT_SYMBOL cleanups 2010-07-12 12:57:54 -07:00
inet_diag.c net: return operator cleanup 2010-09-23 14:33:39 -07:00
inet_fragment.c net/ipv4: EXPORT_SYMBOL cleanups 2010-07-12 12:57:54 -07:00
inet_hashtables.c net/ipv4: EXPORT_SYMBOL cleanups 2010-07-12 12:57:54 -07:00
inet_lro.c
inet_timewait_sock.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
inetpeer.c inetpeer: restore small inet_peer structures 2010-06-16 11:55:39 -07:00
ip_forward.c net-next: remove useless union keyword 2010-06-10 23:31:35 -07:00
ip_fragment.c net: return operator cleanup 2010-09-23 14:33:39 -07:00
ip_gre.c inet: RCU changes in inetdev_by_index() 2010-10-19 03:50:48 -07:00
ip_input.c net: use this_cpu_ptr() 2010-06-28 23:24:29 -07:00
ip_options.c bridge : Sanitize skb before it enters the IP stack 2010-09-19 12:42:34 -07:00
ip_output.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-09-27 01:03:03 -07:00
ip_sockglue.c ipv4: enable getsockopt() for IP_NODEFRAG 2010-09-13 19:57:23 -07:00
ipcomp.c
ipconfig.c ipconfig: send host-name in DHCP requests 2010-06-02 07:05:03 -07:00
ipip.c net: add a core netdev->rx_dropped counter 2010-10-05 14:47:55 -07:00
ipmr.c ipmr: cleanups 2010-10-03 21:50:53 -07:00
Kconfig Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-10-04 11:56:38 -07:00
Makefile PPTP: PPP over IPv4 (Point-to-Point Tunneling Protocol) 2010-08-21 23:05:39 -07:00
netfilter.c Merge branch 'master' of /repos/git/net-next-2.6 2010-06-15 17:31:06 +02:00
proc.c snmp: 64bit ipstats_mib for all arches 2010-06-30 13:31:19 -07:00
protocol.c net: inet_add_protocol() can use cmpxchg() 2010-09-08 21:31:35 -07:00
raw.c net: simplify flags for tx timestamping 2010-08-19 00:08:30 -07:00
route.c net: avoid RCU for NOCACHE dst 2010-10-20 03:02:23 -07:00
syncookies.c syncookies: add support for ECN 2010-06-26 22:00:03 -07:00
sysctl_net_ipv4.c net: reserve ports for applications using fixed port numbers 2010-05-15 23:28:40 -07:00
tcp_bic.c
tcp_cong.c net/ipv4: Eliminate kstrdup memory leak 2010-08-27 19:31:56 -07:00
tcp_cubic.c
tcp_diag.c
tcp_highspeed.c
tcp_htcp.c
tcp_hybla.c TCP: tcp_hybla: Fix integer overflow in slow start increment 2010-06-02 07:15:48 -07:00
tcp_illinois.c
tcp_input.c tcp: sack lost marking fixes 2010-10-17 13:46:33 -07:00
tcp_ipv4.c gro: unexport tcp4_gro_receive and tcp4_gro_complete 2010-08-31 13:37:07 -07:00
tcp_lp.c
tcp_minisocks.c net: return operator cleanup 2010-09-23 14:33:39 -07:00
tcp_output.c net: return operator cleanup 2010-09-23 14:33:39 -07:00
tcp_probe.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
tcp_scalable.c
tcp_timer.c tcp: use correct counters in CA_CWR state too 2010-10-17 13:46:33 -07:00
tcp_vegas.c
tcp_vegas.h
tcp_veno.c
tcp_westwood.c net: return operator cleanup 2010-09-23 14:33:39 -07:00
tcp_yeah.c
tcp.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-10-04 11:56:38 -07:00
tunnel4.c tunnels: missing rcu_assign_pointer() 2010-09-09 15:02:39 -07:00
udp_impl.h
udp.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-09-09 22:27:33 -07:00
udplite.c net/ipv4: EXPORT_SYMBOL cleanups 2010-07-12 12:57:54 -07:00
xfrm4_input.c net/ipv4: EXPORT_SYMBOL cleanups 2010-07-12 12:57:54 -07:00
xfrm4_mode_beet.c
xfrm4_mode_transport.c
xfrm4_mode_tunnel.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
xfrm4_output.c netfilter: ipv4: use NFPROTO values for NF_HOOK invocation 2010-03-25 16:00:30 +01:00
xfrm4_policy.c net dst: use a percpu_counter to track entries 2010-10-11 13:06:53 -07:00
xfrm4_state.c xfrm: Allow different selector family in temporary state 2010-09-20 11:11:38 -07:00
xfrm4_tunnel.c net: struct xfrm_tunnel in read_mostly section 2010-08-30 13:50:45 -07:00