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6eac560407
linux/net/ipv4
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Andi Kleen 6eac560407 tcp: Skip empty hash buckets faster in /proc/net/tcp 
On most systems most of the TCP established/time-wait hash buckets are empty.
When walking the hash table for /proc/net/tcp their read locks would
always be aquired just to find out they're empty. This patch changes the code
to check first if the buckets have any entries before taking the lock, which
is much cheaper than taking a lock. Since the hash tables are large
this makes a measurable difference on processing /proc/net/tcp, 
especially on architectures with slow read_lock (e.g. PPC) 

On a 2GB Core2 system time cat /proc/net/tcp > /dev/null (with a mostly
empty hash table) goes from 0.046s to 0.005s.

On systems with slower atomics (like P4 or POWER4) or larger hash tables
(more RAM) the difference is much higher.

This can be noticeable because there are some daemons around who regularly
scan /proc/net/tcp.

Original idea for this patch from Marcus Meissner, but redone by me.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-28 01:08:02 -07:00
..
ipvs IPVS: Rename ip_vs_proto_ah.c to ip_vs_proto_ah_esp.c 2008-08-27 13:50:37 +10:00
netfilter nf_nat: use secure_ipv4_port_ephemeral() for NAT port randomization 2008-08-18 21:32:32 -07:00
af_inet.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2008-07-26 20:23:44 -07:00
ah4.c [IPSEC]: Fix bogus usage of u64 on input sequence number 2008-02-12 22:50:35 -08:00
arp.c mib: add net to NET_INC_STATS_BH 2008-07-16 20:31:16 -07:00
cipso_ipv4.c cipso: Relax too much careful cipso hash function. 2008-05-13 23:23:55 -07:00
datagram.c mib: add net to IP_INC_STATS_BH 2008-07-16 20:20:11 -07:00
devinet.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
esp4.c ipsec: Interfamily IPSec BEET 2008-08-06 02:39:30 -07:00
fib_frontend.c netns: add namespace parameter to rt_cache_flush 2008-07-05 19:00:44 -07:00
fib_hash.c netns: add namespace parameter to rt_cache_flush 2008-07-05 19:00:44 -07:00
fib_lookup.h [IPV4] FIB_HASH: Reduce memory needs and speedup lookups 2008-01-28 15:02:46 -08:00
fib_rules.c net: add fib_rules_ops to flush_cache method 2008-07-05 19:01:28 -07:00
fib_semantics.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2008-06-13 20:52:39 -07:00
fib_trie.c proc: consolidate per-net single-release callers 2008-07-18 04:07:44 -07:00
icmp.c mib: put icmpmsg statistics on struct net 2008-07-18 04:04:22 -07:00
igmp.c netns: Fix crash by making igmp per namespace 2008-08-13 16:15:57 -07:00
inet_connection_sock.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
inet_diag.c net: remove CVS keywords 2008-06-11 21:00:38 -07:00
inet_fragment.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
inet_hashtables.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
inet_lro.c net/inet_lro: remove setting skb->ip_summed when not LRO-able 2008-06-27 20:09:00 -07:00
inet_timewait_sock.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
inetpeer.c net: remove CVS keywords 2008-06-11 21:00:38 -07:00
ip_forward.c mib: add net to IP_INC_STATS_BH 2008-07-16 20:20:11 -07:00
ip_fragment.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
ip_gre.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2008-05-25 23:26:10 -07:00
ip_input.c mib: put ip statistics on struct net 2008-07-18 04:02:42 -07:00
ip_options.c net: remove CVS keywords 2008-06-11 21:00:38 -07:00
ip_output.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
ip_sockglue.c net: remove CVS keywords 2008-06-11 21:00:38 -07:00
ipcomp.c ipcomp: Fix warnings after ipcomp consolidation. 2008-07-27 03:59:24 -07:00
ipconfig.c netns: Use net_eq() to compare net-namespaces for optimization. 2008-07-19 22:34:43 -07:00
ipip.c net: remove CVS keywords 2008-06-11 21:00:38 -07:00
ipmr.c netns: Use net_eq() to compare net-namespaces for optimization. 2008-07-19 22:34:43 -07:00
Kconfig ipsec: ipcomp - Merge IPComp implementations 2008-07-25 02:54:40 -07:00
Makefile [UDP]: Revert udplite and code split. 2008-03-06 16:22:02 -08:00
netfilter.c [NETFILTER]: Add partial checksum validation helper 2008-04-14 11:15:49 +02:00
proc.c tcp: MD5: Use MIB counter instead of warning for MD5 mismatch. 2008-07-30 03:27:25 -07:00
protocol.c net: remove CVS keywords 2008-06-11 21:00:38 -07:00
raw.c mib: add net to IP_INC_STATS 2008-07-16 20:19:49 -07:00
route.c ipv4: Disable route secret interval on zero interval 2008-08-15 13:44:31 -07:00
syncookies.c syncookies: Make sure ECN is disabled 2008-07-26 02:21:54 -07:00
sysctl_net_ipv4.c net: Add missing extra2 parameter for ip_default_ttl sysctl 2008-08-03 14:06:44 -07:00
tcp_bic.c [TCP]: BIC web page link is corrected. 2008-02-28 22:14:32 -08:00
tcp_cong.c tcp: Limit cwnd growth when deferring for GSO 2008-04-29 03:13:52 -07:00
tcp_cubic.c rename div64_64 to div64_u64 2008-05-01 08:03:58 -07:00
tcp_diag.c net: remove CVS keywords 2008-06-11 21:00:38 -07:00
tcp_highspeed.c [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp_htcp.c [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp_hybla.c net: fix returning void-valued expression warnings 2008-05-01 02:47:38 -07:00
tcp_illinois.c [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp_input.c tcp: Add tcp_parse_aligned_timestamp 2008-08-23 05:12:29 -07:00
tcp_ipv4.c tcp: Skip empty hash buckets faster in /proc/net/tcp 2008-08-28 01:08:02 -07:00
tcp_lp.c [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp_minisocks.c tcp: (whitespace only) fix confusing indentation 2008-08-07 20:27:45 -07:00
tcp_output.c tcp: Fix bitmask test in tcp_syn_options() 2008-07-21 18:45:34 -07:00
tcp_probe.c tcp: correct kcalloc usage 2008-07-10 16:51:32 -07:00
tcp_scalable.c [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp_timer.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
tcp_vegas.c net: fix returning void-valued expression warnings 2008-05-01 02:47:38 -07:00
tcp_vegas.h [TCP]: congestion control API pass RTT in microseconds 2007-07-31 02:27:57 -07:00
tcp_veno.c net: fix returning void-valued expression warnings 2008-05-01 02:47:38 -07:00
tcp_westwood.c [TCP]: congestion control API pass RTT in microseconds 2007-07-31 02:27:57 -07:00
tcp_yeah.c [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28 14:55:41 -08:00
tcp.c net: convert BUG_TRAP to generic WARN_ON 2008-07-25 21:43:18 -07:00
tunnel4.c [IPV4] TUNNEL4: Fix incoming packet length check for inter-protocol tunnel. 2008-06-05 04:02:33 +09:00
udp_impl.h net: change proto destroy method to return void 2008-06-14 17:04:49 -07:00
udp.c udp: Drop socket lock for encapsulated packets 2008-08-09 00:35:05 -07:00
udplite.c mib: put udplite statistics on struct net 2008-07-18 04:03:45 -07:00
xfrm4_input.c [IPSEC]: Fix transport-mode async resume on intput without netfilter 2008-01-28 15:00:10 -08:00
xfrm4_mode_beet.c ipsec: Interfamily IPSec BEET 2008-08-06 02:39:30 -07:00
xfrm4_mode_transport.c [IPSEC]: Use IPv6 calling convention as the convention for x->mode->output 2007-10-10 16:55:54 -07:00
xfrm4_mode_tunnel.c xfrm: fix fragmentation for ipv4 xfrm tunnel 2008-06-17 16:38:23 -07:00
xfrm4_output.c [IPSEC]: Fix inter address family IPsec tunnel handling. 2008-03-24 14:51:51 -07:00
xfrm4_policy.c [NET] NETNS: Omit net_device->nd_net without CONFIG_NET_NS. 2008-03-26 04:39:53 +09:00
xfrm4_state.c [IPSEC]: Fix BEET output 2008-03-26 16:51:09 -07:00
xfrm4_tunnel.c [IPCOMP]: Fix reception of incompressible packets 2008-01-31 19:27:24 -08:00