On Sat, Apr 28, 2012 at 2:46 PM, Yuchung Cheng [off-list ref] wrote:

Implementing the advanced early retransmit (sysctl_tcp_early_retrans==2).
Delays the fast retransmit by an interval of RTT/4. We borrow the
RTO timer to implement the delay. If we receive another ACK or send
a new packet, the timer is cancelled and restored to original RTO
value offset by time elapsed.  When the delayed-ER timer fires,
we enter fast recovery and perform fast retransmit.

Signed-off-by: Yuchung Cheng <redacted>
---
 include/linux/tcp.h   |    4 +-
 include/net/tcp.h     |    3 ++
 net/ipv4/tcp_input.c  |   69 ++++++++++++++++++++++++++++++++++++++++++++-----
 net/ipv4/tcp_output.c |    5 +--
 net/ipv4/tcp_timer.c  |    5 +++
 5 files changed, 74 insertions(+), 12 deletions(-)

Acked-by: Neal Cardwell <ncardwell@google.com>

neal