linux/net/ipv4
Eric Dumazet f278b99ca6 tcp_cubic: refactor code to perform a divide only when needed
Neal Cardwell suggested to not change ca->delay_min
and apply the ack delay cushion only when Hystart ACK train
is still under consideration. This should avoid a 64bit
divide unless needed.

Tested:

40Gbit(mlx4) testbed (with sch_fq as packet scheduler)

$ echo -n 'file tcp_cubic.c +p'  >/sys/kernel/debug/dynamic_debug/control
$ nstat -n;for f in {1..10}; do ./super_netperf 1 -H lpaa24 -l -4000000; done;nstat|egrep "Hystart"
  14815
  16280
  15293
  15563
  11574
  15145
  14789
  18548
  16972
  12520
TcpExtTCPHystartTrainDetect     10                 0.0
TcpExtTCPHystartTrainCwnd       1396               0.0
$ dmesg | tail -10
[ 4873.951350] hystart_ack_train (116 > 93) delay_min 24 (+ ack_delay 69) cwnd 80
[ 4875.155379] hystart_ack_train (55 > 50) delay_min 21 (+ ack_delay 29) cwnd 160
[ 4876.333921] hystart_ack_train (69 > 62) delay_min 23 (+ ack_delay 39) cwnd 130
[ 4877.519037] hystart_ack_train (69 > 60) delay_min 22 (+ ack_delay 38) cwnd 130
[ 4878.701559] hystart_ack_train (87 > 63) delay_min 24 (+ ack_delay 39) cwnd 160
[ 4879.844597] hystart_ack_train (93 > 50) delay_min 21 (+ ack_delay 29) cwnd 216
[ 4880.956650] hystart_ack_train (74 > 67) delay_min 20 (+ ack_delay 47) cwnd 108
[ 4882.098500] hystart_ack_train (61 > 57) delay_min 23 (+ ack_delay 34) cwnd 130
[ 4883.262056] hystart_ack_train (72 > 67) delay_min 21 (+ ack_delay 46) cwnd 130
[ 4884.418760] hystart_ack_train (74 > 67) delay_min 29 (+ ack_delay 38) cwnd 152

10Gbit(bnx2x) testbed (with sch_fq as packet scheduler)

$ echo -n 'file tcp_cubic.c +p'  >/sys/kernel/debug/dynamic_debug/control
$ nstat -n;for f in {1..10}; do ./super_netperf 1 -H lpk52 -l -4000000; done;nstat|egrep "Hystart"
   7050
   7065
   7100
   6900
   7202
   7263
   7189
   6869
   7463
   7034
TcpExtTCPHystartTrainDetect     10                 0.0
TcpExtTCPHystartTrainCwnd       3199               0.0
$ dmesg | tail -10
[  176.920012] hystart_ack_train (161 > 141) delay_min 83 (+ ack_delay 58) cwnd 264
[  179.144645] hystart_ack_train (164 > 159) delay_min 120 (+ ack_delay 39) cwnd 444
[  181.354527] hystart_ack_train (214 > 168) delay_min 125 (+ ack_delay 43) cwnd 436
[  183.539565] hystart_ack_train (170 > 147) delay_min 96 (+ ack_delay 51) cwnd 326
[  185.727309] hystart_ack_train (177 > 160) delay_min 61 (+ ack_delay 99) cwnd 128
[  187.947142] hystart_ack_train (184 > 167) delay_min 123 (+ ack_delay 44) cwnd 367
[  190.166680] hystart_ack_train (230 > 153) delay_min 116 (+ ack_delay 37) cwnd 444
[  192.327285] hystart_ack_train (210 > 206) delay_min 86 (+ ack_delay 120) cwnd 152
[  194.511392] hystart_ack_train (173 > 151) delay_min 94 (+ ack_delay 57) cwnd 239
[  196.736023] hystart_ack_train (149 > 146) delay_min 105 (+ ack_delay 41) cwnd 399

Fixes: 42f3a8aaae ("tcp_cubic: tweak Hystart detection for short RTT flows")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Neal Cardwell <ncardwell@google.com>
Link: https://www.spinics.net/lists/netdev/msg621886.html
Link: https://www.spinics.net/lists/netdev/msg621797.html
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-30 14:44:27 -08:00
..
bpfilter SPDX update for 5.2-rc2, round 1 2019-05-21 12:33:38 -07:00
netfilter netfilter: nf_flow_table_offload: add IPv6 support 2019-11-15 23:44:47 +01:00
af_inet.c net: port < inet_prot_sock(net) --> inet_port_requires_bind_service(net, port) 2019-11-26 13:20:46 -08:00
ah4.c xfrm: remove type and offload_type map from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00
arp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
cipso_ipv4.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 2019-05-21 11:28:45 +02:00
datagram.c inet: stop leaking jiffies on the wire 2019-11-01 14:57:52 -07:00
devinet.c inet: protect against too small mtu values. 2019-12-07 11:55:11 -08:00
esp4.c xfrm: remove get_mtu indirection from xfrm_type 2019-07-01 06:16:40 +02:00
esp4_offload.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2019-07-05 15:01:15 -07:00
fib_frontend.c ipv4: move fib4_has_custom_rules() helper to public header 2019-11-21 14:45:55 -08:00
fib_lookup.h ipv4: Use accessors for fib_info nexthop data 2019-06-04 19:26:49 -07:00
fib_notifier.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_rules.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_semantics.c ipv4: Fix table id reference in fib_sync_down_addr 2019-11-07 16:14:36 -08:00
fib_trie.c ipv4: Remove old route notifications and convert listeners 2019-12-16 16:14:43 -08:00
fou.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
gre_demux.c gre: refetch erspan header from skb->data after pskb_may_pull() 2019-12-07 11:53:27 -08:00
gre_offload.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
icmp.c net: icmp: fix data-race in cmp_global_allow() 2019-11-08 12:32:43 -08:00
igmp.c igmp: uninline ip_mc_validate_checksum() 2019-10-04 14:26:46 -07:00
inet_connection_sock.c net: annotate lockless accesses to sk->sk_max_ack_backlog 2019-11-06 16:14:48 -08:00
inet_diag.c tcp/dccp: fix possible race __inet_lookup_established() 2019-12-13 21:40:49 -08:00
inet_fragment.c inet: frags: re-introduce skb coalescing for local delivery 2019-08-08 15:55:10 -07:00
inet_hashtables.c tcp/dccp: fix possible race __inet_lookup_established() 2019-12-13 21:40:49 -08:00
inet_timewait_sock.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
inetpeer.c inetpeer: fix data-race in inet_putpeer / inet_putpeer 2019-11-07 16:15:56 -08:00
ip_forward.c ipv4: Revert removal of rt_uses_gateway 2019-09-20 18:23:33 -07:00
ip_fragment.c inet: frags: re-introduce skb coalescing for local delivery 2019-08-08 15:55:10 -07:00
ip_gre.c treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
ip_input.c ipv4: use dst hint for ipv4 list receive 2019-11-21 14:45:55 -08:00
ip_options.c netfilter: nf_tables: add support for matching IPv4 options 2019-06-21 18:35:51 +02:00
ip_output.c inet: protect against too small mtu values. 2019-12-07 11:55:11 -08:00
ip_sockglue.c ip_sockglue: Fix missing-check bug in ip_ra_control() 2019-05-25 11:00:50 -07:00
ip_tunnel.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 269 2019-06-05 17:30:29 +02:00
ip_tunnel_core.c lwtunnel: check erspan options before allocating tun_info 2019-11-21 11:47:39 -08:00
ip_vti.c treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
ipcomp.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2019-07-05 15:01:15 -07:00
ipconfig.c net: ipconfig: Wait for deferred device probes 2019-11-20 12:39:53 -08:00
ipip.c ipip: validate header length in ipip_tunnel_xmit 2019-07-25 17:23:40 -07:00
ipmr.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-16 21:51:42 -08:00
ipmr_base.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
Kconfig net: Fix Kconfig indentation, continued 2019-11-21 12:00:21 -08:00
Makefile net: Initial nexthop code 2019-05-28 21:37:30 -07:00
metrics.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
netfilter.c netfilter: ipv4: remove useless export_symbol 2019-01-28 11:32:58 +01:00
netlink.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
nexthop.c net: remove the unnecessary strict_start_type in some policies 2019-11-21 11:46:18 -08:00
ping.c ip: support SO_MARK cmsg 2019-09-13 21:44:19 +02:00
proc.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-17 20:20:36 -07:00
protocol.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
raw.c netfilter: drop bridge nf reset from nf_reset 2019-10-01 18:42:15 +02:00
raw_diag.c net: don't warn in inet diag when IPV6 is disabled 2019-07-03 11:26:35 -07:00
route.c ipv4: use dst hint for ipv4 list receive 2019-11-21 14:45:55 -08:00
syncookies.c tcp: Remove one extra ktime_get_ns() from cookie_init_timestamp 2019-11-07 16:17:52 -08:00
sysctl_net_ipv4.c net-tcp: Disable TCP ssthresh metrics cache by default 2019-12-09 20:17:48 -08:00
tcp.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-22 15:15:05 -08:00
tcp_bbr.c net: annotate lockless accesses to sk->sk_pacing_shift 2019-12-17 22:09:52 -08:00
tcp_bic.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_bpf.c net: skmsg: fix TLS 1.3 crash with full sk_msg 2019-11-28 22:40:29 -08:00
tcp_cdg.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_cong.c tcp: warn if offset reach the maxlen limit when using snprintf 2019-11-20 22:23:36 -08:00
tcp_cubic.c tcp_cubic: refactor code to perform a divide only when needed 2019-12-30 14:44:27 -08:00
tcp_dctcp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tcp_dctcp.h tcp: refactor DCTCP ECN ACK handling 2018-10-10 22:26:00 -07:00
tcp_diag.c net: annotate lockless accesses to sk->sk_max_ack_backlog 2019-11-06 16:14:48 -08:00
tcp_fastopen.c tcp: add TCP_INFO status for failed client TFO 2019-10-25 19:25:37 -07:00
tcp_highspeed.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_htcp.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_hybla.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_illinois.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_input.c tcp: add TCP_INFO status for failed client TFO 2019-10-25 19:25:37 -07:00
tcp_ipv4.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-22 15:15:05 -08:00
tcp_lp.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_metrics.c net-tcp: Disable TCP ssthresh metrics cache by default 2019-12-09 20:17:48 -08:00
tcp_minisocks.c tcp: annotate tp->snd_nxt lockless reads 2019-10-13 10:13:08 -07:00
tcp_nv.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_offload.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tcp_output.c net: annotate lockless accesses to sk->sk_pacing_shift 2019-12-17 22:09:52 -08:00
tcp_rate.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
tcp_recovery.c tcp: introduce tcp_skb_timestamp_us() helper 2018-09-21 19:37:59 -07:00
tcp_scalable.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_timer.c tcp: refactor tcp_retransmit_timer() 2019-12-03 11:52:38 -08:00
tcp_ulp.c tcp: warn if offset reach the maxlen limit when using snprintf 2019-11-20 22:23:36 -08:00
tcp_vegas.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
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 treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_westwood.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_yeah.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tunnel4.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
udp.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-22 16:27:24 -08:00
udp_diag.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
udp_impl.h udp: add missing rehash callback to udplite 2019-01-17 15:01:08 -08:00
udp_offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-22 08:59:24 -04:00
udp_tunnel.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
udplite.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
xfrm4_input.c xfrm: reset transport header back to network header after all input transforms ahave been applied 2018-09-04 10:26:30 +02:00
xfrm4_output.c netfilter: Support iif matches in POSTROUTING 2019-11-15 23:44:48 +01:00
xfrm4_policy.c ipv4: Revert removal of rt_uses_gateway 2019-09-20 18:23:33 -07:00
xfrm4_protocol.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
xfrm4_state.c xfrm: remove eth_proto value from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00
xfrm4_tunnel.c xfrm: remove type and offload_type map from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00