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alistair23-linux/net/ipv4
Eric Dumazet c3916ad932 tcp: smoother receiver autotuning
Back in linux-3.13 (commit b0983d3c9b ("tcp: fix dynamic right sizing"))
I addressed the pressing issues we had with receiver autotuning.

But DRS suffers from extra latencies caused by rcv_rtt_est.rtt_us
drifts. One common problem happens during slow start, since the
apparent RTT measured by the receiver can be inflated by ~50%,
at the end of one packet train.

Also, a single drop can delay read() calls by one RTT, meaning
tcp_rcv_space_adjust() can be called one RTT too late.

By replacing the tri-modal heuristic with a continuous function,
we can offset the effects of not growing 'at the optimal time'.

The curve of the function matches prior behavior if the space
increased by 25% and 50% exactly.

Cost of added multiply/divide is small, considering a TCP flow
typically would run this part of the code few times in its life.

I tested this patch with 100 ms RTT / 1% loss link, 100 runs
of (netperf -l 5), and got an average throughput of 4600 Mbit
instead of 1700 Mbit.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Wei Wang <weiwan@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-12-12 10:53:04 -05:00
..
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2017-11-08 14:22:50 +09:00
Kconfig ip: update policy routing config help 2017-10-12 22:57:11 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
af_inet.c net: accept UFO datagrams from tuntap and packet 2017-11-24 01:37:35 +09:00
ah4.c net: use -ENOSPC for transient busy indication 2017-11-03 22:11:17 +08:00
arp.c ipv4: mark expected switch fall-throughs 2017-10-18 14:10:29 +01:00
cipso_ipv4.c tcp/dccp: fix ireq->opt races 2017-10-21 01:33:19 +01:00
datagram.c
devinet.c net: Add extack to validator_info structs used for address notifier 2017-10-20 13:15:07 +01:00
esp4.c net: use -ENOSPC for transient busy indication 2017-11-03 22:11:17 +08:00
esp4_offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-01 17:42:05 -07:00
fib_frontend.c ipv4: fix validate_source for VRF setup 2017-11-01 21:25:15 +09:00
fib_lookup.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fib_notifier.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fib_rules.c net: fib_rules: Implement notification logic in core 2017-08-03 15:35:59 -07:00
fib_semantics.c tcp: Namespace-ify sysctl_tcp_default_congestion_control 2017-11-15 14:09:52 +09:00
fib_trie.c net: Add extack to fib_notifier_info 2017-11-01 11:50:43 +09:00
fou.c gue: fix remcsum when GRO on and CHECKSUM_PARTIAL boundary is outer UDP 2017-08-01 16:09:14 -07:00
gre_demux.c
gre_offload.c gso: fix payload length when gso_size is zero 2017-10-08 10:12:15 -07:00
icmp.c ipv4: icmp: use BUG_ON instead of if condition followed by BUG 2017-10-24 18:44:42 +09:00
igmp.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
inet_connection_sock.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-30 21:09:24 +09:00
inet_diag.c inet_diag: allow protocols to provide additional data 2017-09-01 18:38:09 -07:00
inet_fragment.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-11-15 11:56:19 -08:00
inet_hashtables.c inet: Add a 2nd listener hashtable (port+addr) 2017-12-03 10:18:28 -05:00
inet_timewait_sock.c Revert "tcp: must block bh in __inet_twsk_hashdance()" 2017-12-05 11:23:58 -05:00
inetpeer.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-05 18:19:22 -07:00
ip_forward.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ip_fragment.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
ip_gre.c ip_gre: Refector the erpsan tunnel code. 2017-12-01 15:33:26 -05:00
ip_input.c IPv4: early demux can return an error code 2017-10-01 03:55:47 +01:00
ip_options.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ip_output.c udp: remove unreachable ufo branches 2017-08-22 14:27:18 -07:00
ip_sockglue.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ip_tunnel.c ipv4: speedup ipv6 tunnels dismantle 2017-09-19 16:32:24 -07:00
ip_tunnel_core.c net: store port/representator id in metadata_dst 2017-06-25 11:42:01 -04:00
ip_vti.c ip_vti: remove the useless err_count check in vti_xmit 2017-11-01 11:57:32 +09:00
ipcomp.c
ipconfig.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ipip.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-30 21:09:24 +09:00
ipmr.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
netfilter.c netfilter: use skb_to_full_sk in ip_route_me_harder 2017-02-28 12:49:36 +01:00
ping.c net: convert sock.sk_refcnt from atomic_t to refcount_t 2017-07-01 07:39:08 -07:00
proc.c tcp: retire FACK loss detection 2017-11-11 18:53:16 +09:00
protocol.c net: Add sysctl to toggle early demux for tcp and udp 2017-03-24 13:17:07 -07:00
raw.c net: ipv4: add second dif to multicast source filter 2017-08-07 11:39:22 -07:00
raw_diag.c net: ipv6: add second dif to raw socket lookups 2017-08-07 11:39:22 -07:00
route.c xfrm: Move dst->path into struct xfrm_dst 2017-11-30 09:54:26 -05:00
syncookies.c tcp: Namespace-ify sysctl_tcp_workaround_signed_windows 2017-10-28 19:24:38 +09:00
sysctl_net_ipv4.c tcp: Namespace-ify sysctl_tcp_default_congestion_control 2017-11-15 14:09:52 +09:00
tcp.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-12-09 22:09:55 -05:00
tcp_bbr.c tcp_bbr: reset long-term bandwidth sampling on loss recovery undo 2017-12-08 13:27:43 -05:00
tcp_bic.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_cdg.c tcp: cdg: make struct tcp_cdg static 2017-10-16 21:24:25 +01:00
tcp_cong.c tcp: Namespace-ify sysctl_tcp_default_congestion_control 2017-11-15 14:09:52 +09:00
tcp_cubic.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_dctcp.c
tcp_diag.c tcp_diag: report TCP MD5 signing keys and addresses 2017-09-01 18:38:09 -07:00
tcp_fastopen.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
tcp_highspeed.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_htcp.c tcp: fix cwnd undo in Reno and HTCP congestion controls 2017-08-06 21:25:10 -07:00
tcp_hybla.c
tcp_illinois.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_input.c tcp: smoother receiver autotuning 2017-12-12 10:53:04 -05:00
tcp_ipv4.c tcp: add tcp_v4_fill_cb()/tcp_v4_restore_cb() 2017-12-03 12:39:14 -05:00
tcp_lp.c tcp: switch TCP TS option (RFC 7323) to 1ms clock 2017-05-17 16:06:01 -04:00
tcp_metrics.c tcp: retire FACK loss detection 2017-11-11 18:53:16 +09:00
tcp_minisocks.c tcp/dccp: block bh before arming time_wait timer 2017-12-01 15:07:43 -05:00
tcp_nv.c tcp_nv: use do_div() instead of expensive div64_u64() 2017-11-04 22:34:52 +09:00
tcp_offload.c tcp: gso: avoid refcount_t warning from tcp_gso_segment() 2017-11-10 18:07:15 +09:00
tcp_output.c tcp: when scheduling TLP, time of RTO should account for current ACK 2017-11-19 12:25:26 +09:00
tcp_probe.c tcp: remove redundant argument from tcp_rcv_established() 2017-07-24 17:28:12 -07:00
tcp_rate.c tcp: invalidate rate samples during SACK reneging 2017-12-08 10:07:02 -05:00
tcp_recovery.c tcp: evaluate packet losses upon RTT change 2017-12-08 14:14:11 -05:00
tcp_scalable.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_timer.c tcp: tcp_mtu_probing() cleanup 2017-11-05 22:14:23 +09:00
tcp_ulp.c tcp: ulp: avoid module refcnt leak in tcp_set_ulp 2017-08-14 22:17:05 -07:00
tcp_vegas.c tcp: fix under-evaluated ssthresh in TCP Vegas 2017-09-29 06:07:00 +01:00
tcp_vegas.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tcp_veno.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_westwood.c tcp: Revert "tcp: remove CA_ACK_SLOWPATH" 2017-08-30 11:20:08 -07:00
tcp_yeah.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tunnel4.c
udp.c udp: Move udp[46]_portaddr_hash() to net/ip[v6].h 2017-12-03 10:18:28 -05:00
udp_diag.c net: ipv6: add second dif to udp socket lookups 2017-08-07 11:39:22 -07:00
udp_impl.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
udp_offload.c net: accept UFO datagrams from tuntap and packet 2017-11-24 01:37:35 +09:00
udp_tunnel.c net: add infrastructure to un-offload UDP tunnel port 2017-07-24 13:52:59 -07:00
udplite.c
xfrm4_input.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xfrm4_mode_beet.c networking: make skb_pull & friends return void pointers 2017-06-16 11:48:39 -04:00
xfrm4_mode_transport.c xfrm: Add encapsulation header offsets while SKB is not encrypted 2017-04-14 10:07:39 +02:00
xfrm4_mode_tunnel.c net: Create and use new helper xfrm_dst_child(). 2017-11-30 09:54:25 -05:00
xfrm4_output.c xfrm: Add an IPsec hardware offloading API 2017-04-14 10:06:10 +02:00
xfrm4_policy.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xfrm4_protocol.c xfrm: input: constify xfrm_input_afinfo 2017-02-09 10:22:17 +01:00
xfrm4_state.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xfrm4_tunnel.c