diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp')
| -rw-r--r-- | pkg/tcpip/transport/tcp/snd.go | 33 |
1 files changed, 31 insertions, 2 deletions
diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go index 284e720c6..0bd421ff4 100644 --- a/pkg/tcpip/transport/tcp/snd.go +++ b/pkg/tcpip/transport/tcp/snd.go @@ -286,8 +286,37 @@ func (s *sender) updateRTO(rtt time.Duration) { if diff < 0 { diff = -diff } - s.rtt.rttvar = (3*s.rtt.rttvar + diff) / 4 - s.rtt.srtt = (7*s.rtt.srtt + rtt) / 8 + // Use RFC6298 standard algorithm to update rttvar and srtt when + // no timestamps are available. + if !s.ep.sendTSOk { + s.rtt.rttvar = (3*s.rtt.rttvar + diff) / 4 + s.rtt.srtt = (7*s.rtt.srtt + rtt) / 8 + } else { + // When we are taking RTT measurements of every ACK then + // we need to use a modified method as specified in + // https://tools.ietf.org/html/rfc7323#appendix-G + if s.outstanding == 0 { + s.rtt.Unlock() + return + } + // Netstack measures congestion window/inflight all in + // terms of packets and not bytes. This is similar to + // how linux also does cwnd and inflight. In practice + // this approximation works as expected. + expectedSamples := math.Ceil(float64(s.outstanding) / 2) + + // alpha & beta values are the original values as recommended in + // https://tools.ietf.org/html/rfc6298#section-2.3. + const alpha = 0.125 + const beta = 0.25 + + alphaPrime := alpha / expectedSamples + betaPrime := beta / expectedSamples + rttVar := (1-betaPrime)*s.rtt.rttvar.Seconds() + betaPrime*diff.Seconds() + srtt := (1-alphaPrime)*s.rtt.srtt.Seconds() + alphaPrime*rtt.Seconds() + s.rtt.rttvar = time.Duration(rttVar * float64(time.Second)) + s.rtt.srtt = time.Duration(srtt * float64(time.Second)) + } } s.rto = s.rtt.srtt + 4*s.rtt.rttvar |