linux/net/ipv4
Eric Dumazet d10473d4e3 tcp: reduce the bloat caused by tcp_is_cwnd_limited()
tcp_is_cwnd_limited() allows GSO/TSO enabled flows to increase
their cwnd to allow a full size (64KB) TSO packet to be sent.

Non GSO flows only allow an extra room of 3 MSS.

For most flows with a BDP below 10 MSS, this results in a bloat
of cwnd reaching 90, and an inflate of RTT.

Thanks to TSO auto sizing, we can restrict the bloat to the number
of MSS contained in a TSO packet (tp->xmit_size_goal_segs), to keep
original intent without performance impact.

Because we keep cwnd small, it helps to keep TSO packet size to their
optimal value.

Example for a 10Mbit flow, with low TCP Small queue limits (no more than
2 skb in qdisc/device tx ring)

Before patch :

lpk51:~# ./ss -i dst lpk52:44862 | grep cwnd
         cubic wscale:6,6 rto:215 rtt:15.875/2.5 mss:1448 cwnd:96
ssthresh:96
send 70.1Mbps unacked:14 rcv_space:29200

After patch :

lpk51:~# ./ss -i dst lpk52:52916 | grep cwnd
         cubic wscale:6,6 rto:206 rtt:5.206/0.036 mss:1448 cwnd:15
ssthresh:14
send 33.4Mbps unacked:4 rcv_space:29200

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Nandita Dukkipati <nanditad@google.com>
Cc: Van Jacobson <vanj@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-02-24 19:13:38 -05:00
..
netfilter netfilter: nf_nat_snmp_basic: fix duplicates in if/else branches 2014-02-14 11:37:36 +01:00
af_inet.c ipv4: introduce hardened ip_no_pmtu_disc mode 2014-01-13 11:22:55 -08:00
ah4.c
arp.c ipv4: arp: update neighbour address when a gratuitous arp is received and arp_accept is set 2014-01-02 00:08:38 -05:00
cipso_ipv4.c ipv4: ERROR: code indent should use tabs where possible 2013-12-26 13:43:21 -05:00
datagram.c net: Remove FLOWI_FLAG_CAN_SLEEP 2013-12-06 07:24:39 +01:00
devinet.c ipv4: Fix runtime WARNING in rtmsg_ifa() 2014-02-06 20:02:15 -08:00
esp4.c net: esp{4,6}: get rid of struct esp_data 2013-10-29 06:39:42 +01:00
fib_frontend.c fib_frontend: fix possible NULL pointer dereference 2014-01-24 15:51:26 -08:00
fib_lookup.h ipv4: make fib_detect_death static 2013-12-28 17:01:46 -05:00
fib_rules.c inet: fix NULL pointer Oops in fib(6)_rule_suppress 2013-12-10 17:54:23 -05:00
fib_semantics.c ipv4: make fib_detect_death static 2013-12-28 17:01:46 -05:00
fib_trie.c seq_file: remove "%n" usage from seq_file users 2013-11-15 09:32:20 +09:00
gre_demux.c gre_offload: statically build GRE offloading support 2014-01-06 20:28:34 -05:00
gre_offload.c net/ipv4: don't use module_init in non-modular gre_offload 2014-01-16 16:08:27 -08:00
icmp.c ipv4: introduce hardened ip_no_pmtu_disc mode 2014-01-13 11:22:55 -08:00
igmp.c net: replace macros net_random and net_srandom with direct calls to prandom 2014-01-14 15:15:25 -08:00
inet_connection_sock.c net: replace macros net_random and net_srandom with direct calls to prandom 2014-01-14 15:15:25 -08:00
inet_diag.c inet_diag: fix inet_diag_dump_icsk() to use correct state for timewait sockets 2014-01-13 22:35:46 -08:00
inet_fragment.c inet: remove old fragmentation hash initializing 2013-10-23 17:01:41 -04:00
inet_hashtables.c
inet_lro.c lro: remove dead code 2013-12-29 16:34:25 -05:00
inet_timewait_sock.c
inetpeer.c ipv4: remove unused function 2013-12-28 17:03:20 -05:00
ip_forward.c net: ip, ipv6: handle gso skbs in forwarding path 2014-02-13 17:17:02 -05:00
ip_fragment.c net: Add utility functions to clear rxhash 2013-12-17 16:36:21 -05:00
ip_gre.c net: gre: use icmp_hdr() to get inner ip header 2014-01-27 20:38:26 -08:00
ip_input.c net: Fix memory leak if TPROXY used with TCP early demux 2014-01-27 16:22:11 -08:00
ip_options.c ipv4: switch and case should be at the same indent 2014-01-02 03:30:36 -05:00
ip_output.c netfilter: nf_tables: fix nf_trace always-on with XT_TRACE=n 2014-02-17 11:20:12 +01:00
ip_sockglue.c ipv6: make IPV6_RECVPKTINFO work for ipv4 datagrams 2014-01-19 19:53:18 -08:00
ip_tunnel_core.c ip_tunnel: Move ip_tunnel_get_stats64 into ip_tunnel_core.c 2014-02-20 02:14:23 -05:00
ip_tunnel.c sit: fix panic with route cache in ip tunnels 2014-02-20 13:13:50 -05:00
ip_vti.c ipv4: be friend with drop monitor 2014-01-18 23:08:02 -08:00
ipcomp.c
ipconfig.c ipv4: ipconfig.c: add parentheses in an if statement 2014-02-14 00:14:23 -05:00
ipip.c ipv4: be friend with drop monitor 2014-01-18 23:08:02 -08:00
ipmr.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-01-18 00:55:41 -08:00
Kconfig
Makefile gre_offload: statically build GRE offloading support 2014-01-06 20:28:34 -05:00
netfilter.c
ping.c ipv6: protect protocols not handling ipv4 from v4 connection/bind attempts 2014-01-21 16:59:19 -08:00
proc.c ipv4: spaces required around that '=' 2014-01-02 03:30:36 -05:00
protocol.c net: remove outdated comment for ipv4 and ipv6 protocol handler 2013-11-28 18:47:51 -05:00
raw.c net: add build-time checks for msg->msg_name size 2014-01-18 23:04:16 -08:00
route.c ipv4: fix counter in_slow_tot 2014-02-17 16:54:42 -05:00
syncookies.c ipv4: fix checkpatch error "space prohibited" 2013-12-26 13:43:21 -05:00
sysctl_net_ipv4.c ipv4: introduce ip_dst_mtu_maybe_forward and protect forwarding path against pmtu spoofing 2014-01-13 11:22:54 -08:00
tcp_bic.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_cong.c tcp: reduce the bloat caused by tcp_is_cwnd_limited() 2014-02-24 19:13:38 -05:00
tcp_cubic.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_diag.c
tcp_fastopen.c tcp: enable sockets to use MSG_FASTOPEN by default 2013-11-04 19:57:47 -05:00
tcp_highspeed.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_htcp.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_hybla.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_illinois.c remove extra definitions of U32_MAX 2014-01-23 16:36:55 -08:00
tcp_input.c tcp: remove 1ms offset in srtt computation 2014-02-06 21:28:06 -08:00
tcp_ipv4.c tcp: delete redundant calls of tcp_mtup_init() 2014-01-21 16:52:31 -08:00
tcp_lp.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_memcontrol.c tcp_memcontrol: Cleanup/fix cg_proto->memory_pressure handling. 2013-12-05 21:01:01 -05:00
tcp_metrics.c tcp: metrics: Handle v6/v4-mapped sockets in tcp-metrics 2014-01-23 12:48:28 -08:00
tcp_minisocks.c ipv6: tcp: fix flowlabel value in ACK messages send from TIME_WAIT 2014-01-17 17:56:33 -08:00
tcp_offload.c tcp: do not export tcp_gso_segment() and tcp_gro_receive() 2014-01-14 18:53:48 -08:00
tcp_output.c net-tcp: fastopen: fix high order allocations 2014-02-22 00:05:21 -05:00
tcp_probe.c ipv4: ERROR: do not initialise globals to 0 or NULL 2013-12-26 13:43:21 -05:00
tcp_scalable.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_timer.c tcp: temporarily disable Fast Open on SYN timeout 2013-10-29 22:50:41 -04:00
tcp_vegas.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_vegas.h
tcp_veno.c tcp: properly handle stretch acks in slow start 2013-11-04 19:57:59 -05:00
tcp_westwood.c
tcp_yeah.c ipv4: ipv4: Cleanup the comments in tcp_yeah.c 2013-12-26 13:43:55 -05:00
tcp.c net-tcp: fastopen: fix high order allocations 2014-02-22 00:05:21 -05:00
tunnel4.c
udp_diag.c
udp_impl.h
udp_offload.c net/ipv4: Use proper RCU APIs for writer-side in udp_offload.c 2014-02-04 20:01:55 -08:00
udp.c net: add build-time checks for msg->msg_name size 2014-01-18 23:04:16 -08:00
udplite.c
xfrm4_input.c
xfrm4_mode_beet.c ipv4: ERROR: code indent should use tabs where possible 2013-12-26 13:43:21 -05:00
xfrm4_mode_transport.c
xfrm4_mode_tunnel.c
xfrm4_output.c
xfrm4_policy.c xfrm: Fix null pointer dereference when decoding sessions 2013-11-01 07:08:46 +01:00
xfrm4_state.c inet: make no_pmtu_disc per namespace and kill ipv4_config 2013-12-18 16:58:20 -05:00
xfrm4_tunnel.c