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| author | David S. Miller <davem@davemloft.net> | 2017-01-14 06:37:18 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-01-14 06:37:18 +0300 |
| commit | 718e14bb292a2e16b506133d191886110417df51 (patch) | |
| tree | a889a29b8bbad8c1c64d339273bcdeea67d63299 /include/linux/tcp.h | |
| parent | 7410191afcaca3a49bb29bfb5e15f81d7b336984 (diff) | |
| parent | 94bdc9785a1136cef6a982b042719783978e8a26 (diff) | |
| download | linux-718e14bb292a2e16b506133d191886110417df51.tar.xz | |
Merge branch 'tcp-RACK-fast-recovery'
Yuchung Cheng says:
====================
tcp: RACK fast recovery
The patch set enables RACK loss detection (draft-ietf-tcpm-rack-01)
to trigger fast recovery with a reordering timer.
Previously RACK has been running in auxiliary mode where it is
used to detect packet losses once the recovery has triggered by
other algorithms (e.g., FACK). By inspecting packet timestamps,
RACK can start ACK-driven repairs timely. A few similar heuristics
are no longer needed and are either removed or disabled to reduce
the complexity of the Linux TCP loss recovery engine:
1. FACK (Forward Acknowledgement)
2. Early Retransmit (RFC5827)
3. thin_dupack (fast recovery on single DUPACK for thin-streams)
4. NCR (Non-Congestion Robustness RFC4653) (RFC4653)
5. Forward Retransmit
After this change, Linux's loss recovery algorithms consist of
1. Conventional DUPACK threshold approach (RFC6675)
2. RACK and Tail Loss Probe (draft-ietf-tcpm-rack-01)
3. RTO plus F-RTO extension (RFC5682)
The patch set has been tested on Google servers extensively and
presented in several IETF meetings. The data suggests that RACK
successfully improves recovery performance:
https://www.ietf.org/proceedings/97/slides/slides-97-tcpm-draft-ietf-tcpm-rack-01.pdf
https://www.ietf.org/proceedings/96/slides/slides-96-tcpm-3.pdf
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/tcp.h')
| -rw-r--r-- | include/linux/tcp.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index fc5848dad7a4..6c22332afb75 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -207,6 +207,8 @@ struct tcp_sock { /* Information of the most recently (s)acked skb */ struct tcp_rack { struct skb_mstamp mstamp; /* (Re)sent time of the skb */ + u32 rtt_us; /* Associated RTT */ + u32 end_seq; /* Ending TCP sequence of the skb */ u8 advanced; /* mstamp advanced since last lost marking */ u8 reord; /* reordering detected */ } rack; @@ -218,12 +220,11 @@ struct tcp_sock { unused:5; u8 nonagle : 4,/* Disable Nagle algorithm? */ thin_lto : 1,/* Use linear timeouts for thin streams */ - thin_dupack : 1,/* Fast retransmit on first dupack */ + unused1 : 1, repair : 1, frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */ u8 repair_queue; - u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */ - syn_data:1, /* SYN includes data */ + u8 syn_data:1, /* SYN includes data */ syn_fastopen:1, /* SYN includes Fast Open option */ syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */ syn_data_acked:1,/* data in SYN is acked by SYN-ACK */ @@ -305,7 +306,6 @@ struct tcp_sock { */ int lost_cnt_hint; - u32 retransmit_high; /* L-bits may be on up to this seqno */ u32 prior_ssthresh; /* ssthresh saved at recovery start */ u32 high_seq; /* snd_nxt at onset of congestion */ |