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| author | Yousuk Seung <ysseung@google.com> | 2017-12-07 13:41:34 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-12-08 10:07:02 -0500 |
| commit | d4761754b4fb2ef8d9a1e9d121c4bec84e1fe292 (patch) | |
| tree | 5a55983a564530e094904c68883a4ce77b69724b /include/linux/tcp.h | |
| parent | 195bd525d5f6e338b948d9a6b25bfaae86291353 (diff) | |
| download | lwn-d4761754b4fb2ef8d9a1e9d121c4bec84e1fe292.tar.gz lwn-d4761754b4fb2ef8d9a1e9d121c4bec84e1fe292.zip | |
tcp: invalidate rate samples during SACK reneging
Mark tcp_sock during a SACK reneging event and invalidate rate samples
while marked. Such rate samples may overestimate bw by including packets
that were SACKed before reneging.
< ack 6001 win 10000 sack 7001:38001
< ack 7001 win 0 sack 8001:38001 // Reneg detected
> seq 7001:8001 // RTO, SACK cleared.
< ack 38001 win 10000
In above example the rate sample taken after the last ack will count
7001-38001 as delivered while the actual delivery rate likely could
be much lower i.e. 7001-8001.
This patch adds a new field tcp_sock.sack_reneg and marks it when we
declare SACK reneging and entering TCP_CA_Loss, and unmarks it after
the last rate sample was taken before moving back to TCP_CA_Open. This
patch also invalidates rate samples taken while tcp_sock.is_sack_reneg
is set.
Fixes: b9f64820fb22 ("tcp: track data delivery rate for a TCP connection")
Signed-off-by: Yousuk Seung <ysseung@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Priyaranjan Jha <priyarjha@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/tcp.h')
| -rw-r--r-- | include/linux/tcp.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index df5d97a85e1a..ca4a6361389b 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -224,7 +224,8 @@ struct tcp_sock { rate_app_limited:1, /* rate_{delivered,interval_us} limited? */ fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */ fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */ - unused:3; + is_sack_reneg:1, /* in recovery from loss with SACK reneg? */ + unused:2; u8 nonagle : 4,/* Disable Nagle algorithm? */ thin_lto : 1,/* Use linear timeouts for thin streams */ unused1 : 1, |