diff options
Diffstat (limited to 'pkg/tcpip/transport/tcp')
| -rw-r--r-- | pkg/tcpip/transport/tcp/snd.go | 63 |
1 files changed, 39 insertions, 24 deletions
diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go index acacb42e4..5862c32f2 100644 --- a/pkg/tcpip/transport/tcp/snd.go +++ b/pkg/tcpip/transport/tcp/snd.go @@ -833,25 +833,6 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se panic("Netstack queues FIN segments without data.") } - segEnd = seg.sequenceNumber.Add(seqnum.Size(seg.data.Size())) - // If the entire segment cannot be accomodated in the receiver - // advertized window, skip splitting and sending of the segment. - // ref: net/ipv4/tcp_output.c::tcp_snd_wnd_test() - // - // Linux checks this for all segment transmits not triggered - // by a probe timer. On this condition, it defers the segment - // split and transmit to a short probe timer. - // ref: include/net/tcp.h::tcp_check_probe_timer() - // ref: net/ipv4/tcp_output.c::tcp_write_wakeup() - // - // Instead of defining a new transmit timer, we attempt to split the - // segment right here if there are no pending segments. - // If there are pending segments, segment transmits are deferred - // to the retransmit timer handler. - if s.sndUna != s.sndNxt && !segEnd.LessThan(end) { - return false - } - if !seg.sequenceNumber.LessThan(end) { return false } @@ -861,14 +842,48 @@ func (s *sender) maybeSendSegment(seg *segment, limit int, end seqnum.Value) (se return false } - // The segment size limit is computed as a function of sender congestion - // window and MSS. When sender congestion window is > 1, this limit can - // be larger than MSS. Ensure that the currently available send space - // is not greater than minimum of this limit and MSS. + // If the whole segment or at least 1MSS sized segment cannot + // be accomodated in the receiver advertized window, skip + // splitting and sending of the segment. ref: + // net/ipv4/tcp_output.c::tcp_snd_wnd_test() + // + // Linux checks this for all segment transmits not triggered by + // a probe timer. On this condition, it defers the segment split + // and transmit to a short probe timer. + // + // ref: include/net/tcp.h::tcp_check_probe_timer() + // ref: net/ipv4/tcp_output.c::tcp_write_wakeup() + // + // Instead of defining a new transmit timer, we attempt to split + // the segment right here if there are no pending segments. If + // there are pending segments, segment transmits are deferred to + // the retransmit timer handler. + if s.sndUna != s.sndNxt { + switch { + case available >= seg.data.Size(): + // OK to send, the whole segments fits in the + // receiver's advertised window. + case available >= s.maxPayloadSize: + // OK to send, at least 1 MSS sized segment fits + // in the receiver's advertised window. + default: + return false + } + } + + // The segment size limit is computed as a function of sender + // congestion window and MSS. When sender congestion window is > + // 1, this limit can be larger than MSS. Ensure that the + // currently available send space is not greater than minimum of + // this limit and MSS. if available > limit { available = limit } - if available > s.maxPayloadSize { + + // If GSO is not in use then cap available to + // maxPayloadSize. When GSO is in use the gVisor GSO logic or + // the host GSO logic will cap the segment to the correct size. + if s.ep.gso == nil && available > s.maxPayloadSize { available = s.maxPayloadSize } |