On Tue, 29 Mar 2016 17:15:52 -0700 Yuchung Cheng <ych...@google.com> wrote:
> For non-SACK connections, cwnd is lowered to inflight plus 3 packets > when the recovery ends. This is an optional feature in the NewReno > RFC 2582 to reduce the potential burst when cwnd is "re-opened" > after recovery and inflight is low. > > This feature is questionably effective because of PRR: when > the recovery ends (i.e., snd_una == high_seq) NewReno holds the > CA_Recovery state for another round trip to prevent false fast > retransmits. But if the inflight is low, PRR will overwrite the > moderated cwnd in tcp_cwnd_reduction() later. > > On the other hand, if the recovery ends because the sender > detects the losses were spurious (e.g., reordering). This feature > unconditionally lowers a reverted cwnd even though nothing > was lost. > > By principle loss recovery module should not update cwnd. Further > pacing is much more effective to reduce burst. Hence this patch > removes the cwnd moderation feature. > > Signed-off-by: Matt Mathis <mattmat...@google.com> > Signed-off-by: Neal Cardwell <ncardw...@google.com> > Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com> I have a concern that this might break Linux builtin protection against hostile receiver sending bogus ACK's. Remember Linux is different than NewReno. You are changing something that has existed for a long long time.
