1. 27 7月, 2013 4 次提交
  2. 25 7月, 2013 24 次提交
  3. 24 7月, 2013 9 次提交
  4. 23 7月, 2013 3 次提交
    • D
      Merge branch 'tcp' · 20ff44aa
      David S. Miller 提交于
      Yuchung Cheng says:
      
      ====================
      This patch series improve RTT sampling in three ways:
      1. Sample RTT during fast recovery and reordering events.
      2. Favor ack-based RTT to timestamps because of broken TS ECR fields
      3. Consolidate the RTT measurement logic.
      ====================
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      20ff44aa
    • Y
      tcp: use RTT from SACK for RTO · ed08495c
      Yuchung Cheng 提交于
      If RTT is not available because Karn's check has failed or no
      new packet is acked, use the RTT measured from SACK to estimate
      the RTO. The sender can continue to estimate the RTO during loss
      recovery or reordering event upon receiving non-partial ACKs.
      
      This also changes when the RTO is re-armed. Previously it is
      only re-armed when some data is cummulatively acknowledged (i.e.,
      SND.UNA advances), but now it is re-armed whenever RTT estimator
      is updated. This feature is particularly useful to reduce spurious
      timeout for buffer bloat including cellular carriers [1], and
      RTT estimation on reordering events.
      
      [1] "An In-depth Study of LTE: Effect of Network Protocol and
       Application Behavior on Performance", In Proc. of SIGCOMM 2013
      Signed-off-by: NYuchung Cheng <ycheng@google.com>
      Acked-by: NNeal Cardwell <ncardwell@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ed08495c
    • Y
      tcp: measure RTT from new SACK · 59c9af42
      Yuchung Cheng 提交于
      Take RTT sample if an ACK selectively acks some sequences that
      have never been retransmitted. The Karn's algorithm does not apply
      even if that ACK (s)acks other retransmitted sequences, because it
      must been generated by an original but perhaps out-of-order packet.
      There is no ambiguity. In case when multiple blocks are newly
      sacked because of ACK losses the earliest block is used to
      measure RTT, similar to cummulative ACKs.
      
      Such RTT samples allow the sender to estimate the RTO during loss
      recovery and packet reordering events. It is still useful even with
      TCP timestamps. That's because during these events the SND.UNA may
      not advance preventing RTT samples from TS ECR (thus the FLAG_ACKED
      check before calling tcp_ack_update_rtt()).  Therefore this new
      RTT source is complementary to existing ACK and TS RTT mechanisms.
      
      This patch does not update the RTO. It is done in the next patch.
      Signed-off-by: NYuchung Cheng <ycheng@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      59c9af42