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Neal Cardwell ed66dfaf23 tcp: when scheduling TLP, time of RTO should account for current ACK 
Fix the TLP scheduling logic so that when scheduling a TLP probe, we
ensure that the estimated time at which an RTO would fire accounts for
the fact that ACKs indicating forward progress should push back RTO
times.

After the following fix:

df92c8394e ("tcp: fix xmit timer to only be reset if data ACKed/SACKed")

we had an unintentional behavior change in the following kind of
scenario: suppose the RTT variance has been very low recently. Then
suppose we send out a flight of N packets and our RTT is 100ms:

t=0: send a flight of N packets
t=100ms: receive an ACK for N-1 packets

The response before df92c8394e that was:
  -> schedule a TLP for now + RTO_interval

The response after df92c8394e is:
  -> schedule a TLP for t=0 + RTO_interval

Since RTO_interval = srtt + RTT_variance, this means that we have
scheduled a TLP timer at a point in the future that only accounts for
RTT_variance. If the RTT_variance term is small, this means that the
timer fires soon.

Before df92c8394e this would not happen, because in that code, when
we receive an ACK for a prefix of flight, we did:

    1) Near the top of tcp_ack(), switch from TLP timer to RTO
       at write_queue_head->paket_tx_time + RTO_interval:
            if (icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
                   tcp_rearm_rto(sk);

    2) In tcp_clean_rtx_queue(), update the RTO to now + RTO_interval:
            if (flag & FLAG_ACKED) {
                   tcp_rearm_rto(sk);

    3) In tcp_ack() after tcp_fastretrans_alert() switch from RTO
       to TLP at now + RTO_interval:
            if (icsk->icsk_pending == ICSK_TIME_RETRANS)
                   tcp_schedule_loss_probe(sk);

In df92c8394e we removed that 3-phase dance, and instead directly
set the TLP timer once: we set the TLP timer in cases like this to
write_queue_head->packet_tx_time + RTO_interval. So if the RTT
variance is small, then this means that this is setting the TLP timer
to fire quite soon. This means if the ACK for the tail of the flight
takes longer than an RTT to arrive (often due to delayed ACKs), then
the TLP timer fires too quickly.

Fixes: df92c8394e ("tcp: fix xmit timer to only be reset if data ACKed/SACKed")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 		2017-11-19 12:25:26 +09:00
..
9p 9p: Implement show_options 2017-07-11 06:08:58 -04:00
bluetooth Bluetooth: Use bt_dev_err and bt_dev_info when possible 2017-10-30 12:25:45 +02:00
caif
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iucv License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
netfilter Modules updates for v4.15 2017-11-15 13:46:33 -08:00
netns tcp: Namespace-ify sysctl_tcp_default_congestion_control 2017-11-15 14:09:52 +09:00
nfc NFC: Add nfc_dbg() macro 2017-04-05 10:15:20 +02:00
phonet net: phonet: mark phonet_protocol as const 2017-10-07 23:15:08 +01:00
sctp sctp: set frag_point in sctp_setsockopt_maxseg correctly 2017-11-18 10:32:41 +09:00
tc_act act_vlan: VLAN action rewrite to use RCU lock/unlock and update 2017-11-10 15:32:20 +09:00
6lowpan.h 6lowpan: Fix IID format for Bluetooth 2017-04-12 22:02:36 +02:00
Space.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
act_api.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-10 10:00:18 +09:00
addrconf.h ipv6: remove IN6_ADDR_HSIZE from addrconf.h 2017-11-05 09:17:27 +09:00
af_ieee802154.h
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af_rxrpc.h rxrpc: Provide functions for allowing cleaner handling of signals 2017-10-18 11:42:48 +01:00
af_unix.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
af_vsock.h VSOCK: use TCP state constants for sk_state 2017-10-05 18:44:17 -07:00
ah.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
arp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
atmclip.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ax25.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ax88796.h
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bond_3ad.h bonding: 3ad: apply ad_actor settings changes immediately 2016-02-09 04:45:49 -05:00
bond_alb.h
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bond_options.h bonding: Prevent duplicate userspace notification 2017-05-27 18:51:41 -04:00
bonding.h bonding: remove rtmsg_ifinfo called after bond_lower_state_changed 2017-10-25 10:54:39 +09:00
busy_poll.h net: fix compilation when busy poll is not enabled 2017-08-11 14:59:24 -07:00
calipso.h net, calipso: convert calipso_doi.refcount from atomic_t to refcount_t 2017-07-04 22:35:16 +01:00
cfg80211-wext.h
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cfg80211.h cfg80211/nl80211: add a port authorized event 2017-10-02 14:08:27 +02:00
cfg802154.h ieee802154: add netns support 2016-07-08 12:20:57 +02:00
checksum.h csum: eliminate sparse warning in remcsum_unadjust() 2017-01-20 12:12:13 -05:00
cipso_ipv4.h net, ipv4: convert cipso_v4_doi.refcount from atomic_t to refcount_t 2017-07-04 01:29:04 -07:00
cls_cgroup.h cls_cgroup: get sk_classid only from full sockets 2016-04-19 20:09:25 -04:00
codel.h codel: split into multiple files 2016-04-25 16:44:27 -04:00
codel_impl.h codel: split into multiple files 2016-04-25 16:44:27 -04:00
codel_qdisc.h net_sched: fq_codel: cache skb->truesize into skb->cb 2016-06-25 12:19:35 -04:00
compat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
datalink.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dcbevent.h
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dcbnl.h
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devlink.h devlink: Add IPv6 header for dpipe 2017-08-31 14:42:19 -07:00
dn.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
dn_dev.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dn_fib.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dn_neigh.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dn_nsp.h net/decnet: Convert timers to use timer_setup() 2017-10-18 12:39:36 +01:00
dn_route.h
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dsa.h net: dsa: Support prepended Broadcom tag 2017-11-13 10:34:54 +09:00
dsfield.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dst.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
dst_cache.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dst_metadata.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
dst_ops.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
erspan.h gre: introduce native tunnel support for ERSPAN 2017-08-22 14:29:30 -07:00
esp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ethoc.h
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fib_notifier.h net: Add extack to fib_notifier_info 2017-11-01 11:50:43 +09:00
fib_rules.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
firewire.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
flow.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
flow_dissector.h tipc: improve link resiliency when rps is activated 2017-11-11 15:36:05 +09:00
fou.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fq.h fq: support filtering a given tin 2017-10-11 09:49:34 +02:00
fq_impl.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-30 21:09:24 +09:00
garp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gen_stats.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
genetlink.h genetlink: fix genlmsg_nlhdr() 2017-11-16 10:49:00 +09:00
geneve.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gre.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gro_cells.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gtp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gue.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hwbm.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
icmp.h net: snmp: kill STATS_BH macros 2016-04-27 22:48:25 -04:00
ieee80211_radiotap.h wireless: radiotap: rewrite the radiotap header file 2017-01-25 16:00:33 +01:00
ieee802154_netdev.h mac802154: constify ieee802154_llsec_ops structure 2016-01-04 20:40:41 +01:00
if_inet6.h net, ipv6: convert ifacaddr6.aca_refcnt from atomic_t to refcount_t 2017-07-04 01:29:04 -07:00
ife.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ila.h ila: Add generic ILA translation facility 2015-12-15 23:25:20 -05:00
inet6_connection_sock.h inet: drop ->bind_conflict 2017-01-18 13:04:28 -05:00
inet6_hashtables.h net: ipv6: add second dif to inet6 socket lookups 2017-08-07 11:39:22 -07:00
inet_common.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
inet_connection_sock.h inet/connection_sock: Convert timers to use timer_setup() 2017-10-18 12:39:55 +01:00
inet_ecn.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
inet_frag.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
inet_hashtables.h net: ipv4: add second dif to inet socket lookups 2017-08-07 11:39:21 -07:00
inet_sock.h Merge branch 'akpm' (patches from Andrew) 2017-11-15 19:42:40 -08:00
inet_timewait_sock.h kmemcheck: remove annotations 2017-11-15 18:21:04 -08:00
inetpeer.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ip.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-08-21 17:06:42 -07:00
ip6_checksum.h ipv6: Pass proto to csum_ipv6_magic as __u8 instead of unsigned short 2016-03-13 23:55:13 -04:00
ip6_fib.h ipv6: take care of rt6_stats 2017-10-07 21:22:58 +01:00
ip6_route.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
ip6_tunnel.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ip_fib.h net: ipv4: remove fib_weight 2017-09-29 06:19:32 +01:00
ip_tunnels.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
ip_vs.h Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
ipcomp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ipconfig.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ipv6.h net: Remove unused skb_shared_info member 2017-11-11 22:09:40 +09:00
ipx.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
iw_handler.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kcm.h kcm: Use stream parser 2016-08-17 19:36:23 -04:00
l3mdev.h net: ipv4: Do not drop to make_route if oif is l3mdev 2016-10-13 12:05:26 -04:00
lapb.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
lib80211.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
llc.h net, llc: convert llc_sap.refcnt from atomic_t to refcount_t 2017-07-04 22:35:15 +01:00
llc_c_ac.h net: LLC: Convert timers to use timer_setup() 2017-10-25 12:06:25 +09:00
llc_c_ev.h
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llc_c_st.h
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llc_conn.h
…
llc_if.h
…
llc_pdu.h
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llc_s_ac.h
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llc_s_ev.h
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llc_s_st.h
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llc_sap.h
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lwtunnel.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mac80211.h mac80211: add documentation to ieee80211_rx_ba_offl() 2017-09-21 11:42:00 +02:00
mac802154.h ieee802154: cleanup WARN_ON for fc fetch 2016-07-08 13:23:12 +02:00
mip6.h
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mld.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mpls.h openvswitch: use mpls_hdr 2016-10-03 02:00:22 -04:00
mpls_iptunnel.h net: mpls: Increase max number of labels for lwt encap 2017-04-01 20:21:44 -07:00
mrp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ncsi.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ndisc.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
neighbour.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
net_namespace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
net_ratelimit.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
netevent.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
netlabel.h net: convert netlbl_lsm_cache.refcount from atomic_t to refcount_t 2017-07-01 07:39:09 -07:00
netlink.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
netprio_cgroup.h
…
netrom.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nexthop.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nl802154.h ieee802154: add netns support 2016-07-08 12:20:57 +02:00
nsh.h openvswitch: enable NSH support 2017-11-08 16:12:33 +09:00
p8022.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ping.h net: ping: make ping_v6_sendmsg static 2016-03-23 22:09:58 -04:00
pkt_cls.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-10 10:00:18 +09:00
pkt_sched.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
pptp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
protocol.h IPv4: early demux can return an error code 2017-10-01 03:55:47 +01:00
psample.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
psnap.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
raw.h net: ipv4: add second dif to raw socket lookups 2017-08-07 11:39:21 -07:00
rawv6.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
red.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
regulatory.h
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request_sock.h tcp: socket option to set TCP fast open key 2017-10-20 13:21:36 +01:00
rose.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
route.h udp: perform source validation for mcast early demux 2017-10-01 03:55:47 +01:00
rtnetlink.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
sch_generic.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
scm.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
secure_seq.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
seg6.h ipv6: sr: add support for ip4ip6 encapsulation 2017-08-25 17:10:23 -07:00
seg6_hmac.h ipv6: sr: add core files for SR HMAC support 2016-11-09 20:40:06 -05:00
slhc_vj.h
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smc.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
snmp.h net: snmp: fix 64bit stats on 32bit arches 2016-04-28 11:49:45 -04:00
sock.h Merge branch 'akpm' (patches from Andrew) 2017-11-15 19:42:40 -08:00
sock_reuseport.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
strparser.h strparser: Use delayed work instead of timer for msg timeout 2017-10-25 10:37:11 +09:00
switchdev.h net: bridge: Add/del switchdev object on host join/leave 2017-11-10 13:41:40 +09:00
tcp.h tcp: when scheduling TLP, time of RTO should account for current ACK 2017-11-19 12:25:26 +09:00
tcp_states.h
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timewait_sock.h
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tipc.h tipc: improve link resiliency when rps is activated 2017-11-11 15:36:05 +09:00
tls.h uapi: fix linux/tls.h userspace compilation error 2017-11-15 13:54:18 +09:00
transp_v6.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tso.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tun_proto.h vxlan: factor out VXLAN-GPE next protocol 2017-08-29 15:16:52 -07:00
udp.h IPv4: early demux can return an error code 2017-10-01 03:55:47 +01:00
udp_tunnel.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
udplite.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vsock_addr.h
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vxlan.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
wext.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
wimax.h
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x25.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
x25device.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xfrm.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00