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linux/net/ipv4
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Yuchung Cheng 94bdc9785a tcp: disable fack by default 
This patch disables FACK by default as RACK is the successor of FACK
(inspired by the insights behind FACK).

FACK[1] in Linux works as follows: a packet P is deemed lost,
if packet Q of higher sequence is s/acked and P and Q are distant
by at least dupthresh number of packets in sequence space.

FACK is more aggressive than the IETF recommened recovery for SACK
(RFC3517 A Conservative Selective Acknowledgment (SACK)-based Loss
 Recovery Algorithm for TCP), because a single SACK may trigger
fast recovery. This obviously won't work well with reordering so
FACK is dynamically disabled upon detecting reordering.

RACK supersedes FACK by using time distance instead of sequence
distance. On reordering, RACK waits for a quarter of RTT receiving
a single SACK before starting recovery. (the timer can be made more
adaptive in the future by measuring reordering distance in time,
but currently RTT/4 seem to work well.) Once the recovery starts,
RACK behaves almost like FACK because it reduces the reodering
window to 1ms, so it fast retransmits quickly. In addition RACK
can detect loss retransmission as it does not care about the packet
sequences (being repeated or not), which is extremely useful when
the connection is going through a traffic policer.

Google server experiments indicate that disabling FACK after enabling
RACK has negligible impact on the overall loss recovery performance
with more reordering events detected.  But we still keep the FACK
implementation for backup if RACK has bugs that needs to be disabled.

[1] M. Mathis, J. Mahdavi, "Forward Acknowledgment: Refining
TCP Congestion Control," In Proceedings of SIGCOMM '96, August 1996.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-13 22:37:16 -05:00
..
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2017-01-05 11:49:57 -05:00
af_inet.c ipv4: Namespaceify tcp_tw_recycle and tcp_max_tw_buckets knob 2016-12-29 11:38:31 -05:00
ah4.c
arp.c net: rename NET_{ADD|INC}_STATS_BH() 2016-04-27 22:48:24 -04:00
cipso_ipv4.c Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/selinux into next 2016-07-07 10:15:34 +10:00
datagram.c
devinet.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
esp4.c esp4: Fix integrity verification when ESN are used 2016-11-30 11:09:39 +01:00
fib_frontend.c ipv4: Do not allow MAIN to be alias for new LOCAL w/ custom rules 2017-01-03 09:38:34 -05:00
fib_lookup.h
fib_rules.c switchdev: remove FIB offload infrastructure 2016-09-28 04:48:00 -04:00
fib_semantics.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-01-11 14:43:39 -05:00
fib_trie.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
fou.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-10-30 12:42:58 -04:00
gre_demux.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-06-30 05:03:36 -04:00
gre_offload.c net: add recursion limit to GRO 2016-10-20 14:32:22 -04:00
icmp.c net: for rate-limited ICMP replies save one atomic operation 2017-01-09 15:49:12 -05:00
igmp.c igmp: Make igmp group member RFC 3376 compliant 2017-01-02 13:01:03 -05:00
inet_connection_sock.c inet: Fix get port to handle zero port number with soreuseport set 2016-12-17 11:13:19 -05:00
inet_diag.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
inet_fragment.c net: disable fragment reassembly if high_thresh is zero 2016-06-05 22:56:42 -04:00
inet_hashtables.c net: Require exact match for TCP socket lookups if dif is l3mdev 2016-10-17 10:17:05 -04:00
inet_timewait_sock.c ipv4: Namespaceify tcp_tw_recycle and tcp_max_tw_buckets knob 2016-12-29 11:38:31 -05:00
inetpeer.c
ip_forward.c ipv4: allow local fragmentation in ip_finish_output_gso() 2016-11-03 16:10:26 -04:00
ip_fragment.c net: rename IP_INC_STATS_BH() 2016-04-27 22:48:23 -04:00
ip_gre.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ip_input.c net: VRF: Pass original iif to ip_route_input() 2016-09-16 04:24:07 -04:00
ip_options.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ip_output.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ip_sockglue.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-01-05 11:03:07 -05:00
ip_tunnel_core.c net: make ndo_get_stats64 a void function 2017-01-08 17:51:44 -05:00
ip_tunnel.c netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
ip_vti.c netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
ipcomp.c
ipconfig.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ipip.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ipmr.c ipmr: improve hash scalability 2017-01-12 16:48:26 -05:00
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-12-03 12:29:53 -05:00
Makefile net: ip, diag -- Add diag interface for raw sockets 2016-10-23 19:35:24 -04:00
netfilter.c netfilter: Update ip_route_me_harder to consider L3 domain 2016-11-24 12:44:36 +01:00
ping.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-16 10:24:44 -08:00
proc.c ipv4: Namespaceify tcp_tw_recycle and tcp_max_tw_buckets knob 2016-12-29 11:38:31 -05:00
protocol.c
raw_diag.c net: ip, raw_diag -- Use jump for exiting from nested loop 2016-11-03 15:25:26 -04:00
raw.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
route.c net: ipv4: remove disable of bottom half in inet_rtm_getroute 2017-01-09 13:54:44 -05:00
syncookies.c syncookies: use SipHash in place of SHA1 2017-01-09 13:58:57 -05:00
sysctl_net_ipv4.c tcp: remove thin_dupack feature 2017-01-13 22:37:16 -05:00
tcp_bbr.c tcp_bbr: add a state transition diagram and accompanying comment 2016-10-29 17:12:43 -04:00
tcp_bic.c tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_cdg.c tcp: cdg: rename struct minmax in tcp_cdg.c to avoid a naming conflict 2016-09-21 00:22:59 -04:00
tcp_cong.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-22 13:27:16 -05:00
tcp_cubic.c tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_dctcp.c Revert "dctcp: update cwnd on congestion event" 2016-12-06 11:34:24 -05:00
tcp_diag.c net: diag: Fix refcnt leak in error path destroying socket 2016-08-23 23:11:36 -07:00
tcp_fastopen.c tcp: fastopen: avoid negative sk_forward_alloc 2016-09-08 16:08:10 -07:00
tcp_highspeed.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_htcp.c tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_hybla.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_illinois.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_input.c tcp: disable fack by default 2017-01-13 22:37:16 -05:00
tcp_ipv4.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_lp.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_metrics.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_minisocks.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_nv.c tcp: add NV congestion control 2016-06-10 23:07:49 -07:00
tcp_offload.c gso: Support partial splitting at the frag_list pointer 2016-09-19 20:59:34 -04:00
tcp_output.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_probe.c net: ipv4: tcp_probe: Replace timespec with timespec64 2016-03-01 17:18:44 -05:00
tcp_rate.c tcp: export data delivery rate 2016-09-21 00:23:00 -04:00
tcp_recovery.c tcp: enable RACK loss detection to trigger recovery 2017-01-13 22:37:16 -05:00
tcp_scalable.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_timer.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_vegas.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_vegas.h tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_veno.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_westwood.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_yeah.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp.c tcp: remove thin_dupack feature 2017-01-13 22:37:16 -05:00
tunnel4.c tunnels: correct conditional build of MPLS and IPv6 2016-07-11 13:27:06 -07:00
udp_diag.c net: inet: diag: expose the socket mark to privileged processes. 2016-09-08 16:13:09 -07:00
udp_impl.h udplite: call proper backlog handlers 2016-11-24 15:32:14 -05:00
udp_offload.c net: add recursion limit to GRO 2016-10-20 14:32:22 -04:00
udp_tunnel.c net: Remove deprecated tunnel specific UDP offload functions 2016-06-17 20:23:32 -07:00
udp.c udp: inuse checks can quit early for reuseport 2017-01-06 20:56:48 -05:00
udplite.c udplite: call proper backlog handlers 2016-11-24 15:32:14 -05:00
xfrm4_input.c
xfrm4_mode_beet.c
xfrm4_mode_transport.c
xfrm4_mode_tunnel.c
xfrm4_output.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-10-24 06:54:12 -07:00
xfrm4_policy.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-12 15:52:44 -07:00
xfrm4_protocol.c
xfrm4_state.c
xfrm4_tunnel.c