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authorYuchung Cheng <ycheng@google.com>2017-01-12 22:11:39 -0800
committerDavid S. Miller <davem@davemloft.net>2017-01-13 22:37:16 -0500
commitbec41a11dd3dc8c54f766b4f494140ca92ba7c10 (patch)
tree62a888654cc55636c2ab85adf331db2361aae118 /Documentation/networking
parent840a3cbe89694fad75578856976f180e852e69aa (diff)
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tcp: remove early retransmit
This patch removes the support of RFC5827 early retransmit (i.e., fast recovery on small inflight with <3 dupacks) because it is subsumed by the new RACK loss detection. More specifically when RACK receives DUPACKs, it'll arm a reordering timer to start fast recovery after a quarter of (min)RTT, hence it covers the early retransmit except RACK does not limit itself to specific inflight or dupack numbers. 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>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/ip-sysctl.txt19
1 files changed, 5 insertions, 14 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 7dd65c9cf707..7de2cf79e16f 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -246,21 +246,12 @@ tcp_dsack - BOOLEAN
Allows TCP to send "duplicate" SACKs.
tcp_early_retrans - INTEGER
- Enable Early Retransmit (ER), per RFC 5827. ER lowers the threshold
- for triggering fast retransmit when the amount of outstanding data is
- small and when no previously unsent data can be transmitted (such
- that limited transmit could be used). Also controls the use of
- Tail loss probe (TLP) that converts RTOs occurring due to tail
- losses into fast recovery (draft-dukkipati-tcpm-tcp-loss-probe-01).
+ Tail loss probe (TLP) converts RTOs occurring due to tail
+ losses into fast recovery (draft-ietf-tcpm-rack). Note that
+ TLP requires RACK to function properly (see tcp_recovery below)
Possible values:
- 0 disables ER
- 1 enables ER
- 2 enables ER but delays fast recovery and fast retransmit
- by a fourth of RTT. This mitigates connection falsely
- recovers when network has a small degree of reordering
- (less than 3 packets).
- 3 enables delayed ER and TLP.
- 4 enables TLP only.
+ 0 disables TLP
+ 3 or 4 enables TLP
Default: 3
tcp_ecn - INTEGER