1. 30 9月, 2015 38 次提交
  2. 29 9月, 2015 2 次提交
    • J
      net: help compiler generate better code in eth_get_headlen · 8a4683a5
      Jesper Dangaard Brouer 提交于
      Noticed that the compiler (gcc version 4.8.5 20150623 (Red Hat 4.8.5-4) (GCC))
      generated suboptimal assembler code in eth_get_headlen().
      
      This early return coding style is usually not an issue, on super scalar CPUs,
      but the compiler choose to put the return statement after this very unlikely
      branch, thus creating larger jump down to the likely code path.
      
      Performance wise, I could measure slightly less L1-icache-load-misses
      and less branch-misses, and an improvement of 1 nanosec with an IP-forwarding
      use-case with 257 bytes packets with ixgbe (CPU i7-4790K @ 4.00GHz).
      Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      8a4683a5
    • B
      tcp: Fix CWV being too strict on thin streams · d2e1339f
      Bendik Rønning Opstad 提交于
      Application limited streams such as thin streams, that transmit small
      amounts of payload in relatively few packets per RTT, can be prevented
      from growing the CWND when in congestion avoidance. This leads to
      increased sojourn times for data segments in streams that often transmit
      time-dependent data.
      
      Currently, a connection is considered CWND limited only after having
      successfully transmitted at least one packet with new data, while at the
      same time failing to transmit some unsent data from the output queue
      because the CWND is full. Applications that produce small amounts of
      data may be left in a state where it is never considered to be CWND
      limited, because all unsent data is successfully transmitted each time
      an incoming ACK opens up for more data to be transmitted in the send
      window.
      
      Fix by always testing whether the CWND is fully used after successful
      packet transmissions, such that a connection is considered CWND limited
      whenever the CWND has been filled. This is the correct behavior as
      specified in RFC2861 (section 3.1).
      
      Cc: Andreas Petlund <apetlund@simula.no>
      Cc: Carsten Griwodz <griff@simula.no>
      Cc: Jonas Markussen <jonassm@ifi.uio.no>
      Cc: Kenneth Klette Jonassen <kennetkl@ifi.uio.no>
      Cc: Mads Johannessen <madsjoh@ifi.uio.no>
      Signed-off-by: NBendik Rønning Opstad <bro.devel+kernel@gmail.com>
      Acked-by: NEric Dumazet <edumazet@google.com>
      Tested-by: NEric Dumazet <edumazet@google.com>
      Acked-by: NNeal Cardwell <ncardwell@google.com>
      Tested-by: NNeal Cardwell <ncardwell@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d2e1339f