linux/net
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
..
6lowpan License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
9p make sock_alloc_file() do sock_release() on failures 2017-12-05 18:39:29 -05:00
802 treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
8021q Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-12 09:17:05 +09:00
appletalk treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
atm atm: mpoa: remove 32-bit timekeeping 2017-11-30 09:26:32 -05:00
ax25 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
batman-adv treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
bluetooth treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
bpf
bridge net: use rtnl_register_module where needed 2017-12-04 11:32:39 -05:00
caif License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
can net: use rtnl_register_module where needed 2017-12-04 11:32:39 -05:00
ceph We have a set of file locking improvements from Zheng, rbd rw/ro 2017-11-21 05:38:32 -10:00
core rtnetlink: fix typo in GSO max segments 2017-12-11 09:45:59 -05:00
dcb
dccp dccp: CVE-2017-8824: use-after-free in DCCP code 2017-12-05 18:08:53 -05:00
decnet net: use rtnl_register_module where needed 2017-12-04 11:32:39 -05:00
dns_resolver KEYS: Fix race between updating and finding a negative key 2017-10-18 09:12:40 +01:00
dsa net: dsa: Allow compiling out legacy support 2017-12-07 14:14:54 -05:00
ethernet
hsr net: hsr: Convert timers to use timer_setup() 2017-10-25 13:00:27 +09:00
ieee802154 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
ife MAINTAINERS: Update Yotam's E-mail 2017-11-01 12:19:03 +09:00
ipv4 tcp: smoother receiver autotuning 2017-12-12 10:53:04 -05:00
ipv6 rhashtable: Change rhashtable_walk_start to return void 2017-12-11 09:58:38 -05:00
ipx Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
iucv
kcm make sock_alloc_file() do sock_release() on failures 2017-12-05 18:39:29 -05:00
key af_key: replace BUG_ON on WARN_ON in net_exit hook 2017-11-14 15:45:52 +09:00
l2tp l2tp: exit_net cleanup check added 2017-11-14 15:45:53 +09:00
l3mdev
lapb treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts 2017-11-21 16:35:54 -08:00
llc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-11-15 11:56:19 -08:00
mac80211 rhashtable: Change rhashtable_walk_start to return void 2017-12-11 09:58:38 -05:00
mac802154 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
mpls net: use rtnl_register_module where needed 2017-12-04 11:32:39 -05:00
ncsi treewide: setup_timer() -> timer_setup() (2 field) 2017-11-21 15:57:09 -08:00
netfilter rhashtable: Change rhashtable_walk_start to return void 2017-12-11 09:58:38 -05:00
netlabel net/netlabel: Add list_next_rcu() in rcu_dereference(). 2017-11-18 10:32:41 +09:00
netlink netlink: convert netlink tap spinlock to mutex 2017-12-11 10:56:55 -05:00
netrom treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts 2017-11-21 16:35:54 -08:00
nfc treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
nsh openvswitch: enable NSH support 2017-11-08 16:12:33 +09:00
openvswitch openvswitch: do not propagate headroom updates to internal port 2017-12-02 21:14:59 -05:00
packet net/packet: fix a race in packet_bind() and packet_notifier() 2017-11-28 11:13:30 -05:00
phonet net: use rtnl_register_module where needed 2017-12-04 11:32:39 -05:00
psample MAINTAINERS: Update Yotam's E-mail 2017-11-01 12:19:03 +09:00
qrtr net: use rtnl_register_module where needed 2017-12-04 11:32:39 -05:00
rds Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-12-09 22:09:55 -05:00
rfkill
rose treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts 2017-11-21 16:35:54 -08:00
rxrpc rxrpc: Use correct netns source in rxrpc_release_sock() 2017-12-03 10:05:20 -05:00
sched Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-12-09 22:09:55 -05:00
sctp sctp: add support for the process of unordered idata 2017-12-11 11:23:05 -05:00
smc smc: support variable CLC proposal messages 2017-12-07 15:03:12 -05:00
strparser strparser: Use delayed work instead of timer for msg timeout 2017-10-25 10:37:11 +09:00
sunrpc NFS client fixes for Linux 4.15-rc2 2017-12-01 20:04:20 -05:00
switchdev net: bridge: Add/del switchdev object on host join/leave 2017-11-10 13:41:40 +09:00
tipc rhashtable: Change rhashtable_walk_start to return void 2017-12-11 09:58:38 -05:00
tls tls: don't override sk_write_space if tls_set_sw_offload fails. 2017-11-14 16:26:35 +09:00
unix Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
vmw_vsock VSOCK: fix outdated sk_state value in hvs_release() 2017-12-05 15:07:37 -05:00
wimax License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
wireless Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-29 13:10:25 -08:00
x25 treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts 2017-11-21 16:35:54 -08:00
xfrm xfrm: Stop using dst->next in bundle construction. 2017-11-30 09:54:27 -05:00
compat.c
Kconfig
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
socket.c make sock_alloc_file() do sock_release() on failures 2017-12-05 18:39:29 -05:00
sysctl_net.c