linux/include/net/netns
David Morley ccce324dab tcp: make the first N SYN RTO backoffs linear
Currently the SYN RTO schedule follows an exponential backoff
scheme, which can be unnecessarily conservative in cases where
there are link failures. In such cases, it's better to
aggressively try to retransmit packets, so it takes routers
less time to find a repath with a working link.

We chose a default value for this sysctl of 4, to follow
the macOS and IOS backoff scheme of 1,1,1,1,1,2,4,8, ...
MacOS and IOS have used this backoff schedule for over
a decade, since before this 2009 IETF presentation
discussed the behavior:
https://www.ietf.org/proceedings/75/slides/tcpm-1.pdf

This commit makes the SYN RTO schedule start with a number of
linear backoffs given by the following sysctl:
* tcp_syn_linear_timeouts

This changes the SYN RTO scheme to be: init_rto_val for
tcp_syn_linear_timeouts, exp backoff starting at init_rto_val

For example if init_rto_val = 1 and tcp_syn_linear_timeouts = 2, our
backoff scheme would be: 1, 1, 1, 2, 4, 8, 16, ...

Signed-off-by: David Morley <morleyd@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Tested-by: David Morley <morleyd@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230509180558.2541885-1-morleyd.kernel@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
History 2023-05-11 10:31:16 +02:00
..
bpf.h bpf: Invert the dependency between bpf-netns.h and netns/bpf.h 2021-12-29 20:03:05 -08:00
can.h net: add missing includes and forward declarations under net/ 2022-07-22 12:53:22 +01:00
conntrack.h netfilter: ctnetlink: make event listener tracking global 2023-02-22 00:28:47 +01:00
core.h net: make default_rps_mask a per netns attribute 2023-02-20 11:22:54 +00:00
flow_table.h netfilter: nf_flow_table: count pending offload workqueue tasks 2022-07-11 16:25:14 +02:00
generic.h netns: Replace zero-length array with DECLARE_FLEX_ARRAY() helper 2022-09-28 18:51:47 -07:00
hash.h netns: provide pure entropy for net_hash_mix() 2019-03-28 17:00:45 -07:00
ieee802154_6lowpan.h net: dynamically allocate fqdir structures 2019-05-26 14:08:05 -07:00
ipv4.h tcp: make the first N SYN RTO backoffs linear 2023-05-11 10:31:16 +02:00
ipv6.h ipv6: add icmpv6_error_anycast_as_unicast for ICMPv6 2023-04-20 20:07:50 -07:00
mctp.h net: add missing includes and forward declarations under net/ 2022-07-22 12:53:22 +01:00
mib.h net: reorganize fields in netns_mib 2021-04-02 14:31:44 -07:00
mpls.h net: add missing includes and forward declarations under net/ 2022-07-22 12:53:22 +01:00
netfilter.h Remove DECnet support from kernel 2022-08-22 14:26:30 +01:00
nexthop.h net: add missing includes and forward declarations under net/ 2022-07-22 12:53:22 +01:00
nftables.h net: remove obsolete members from struct net 2021-04-06 00:34:53 +02:00
packet.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sctp.h sctp: add dif and sdif check in asoc and ep lookup 2022-11-18 11:42:54 +00:00
smc.h net/smc: Unbind r/w buffer size from clcsock and make them tunable 2022-09-22 12:58:21 +02:00
unix.h net: add missing includes and forward declarations under net/ 2022-07-22 12:53:22 +01:00
xdp.h net: xsk: Don't include <linux/rculist.h> 2022-12-06 20:04:34 -08:00
xfrm.h xfrm: rework default policy structure 2022-03-18 07:23:12 +01:00