1. 14 Aug, 2012 2 commits
  2. 09 Aug, 2012 7 commits
  3. 07 Aug, 2012 4 commits
  4. 06 Aug, 2012 4 commits
    • Eric Dumazet's avatar
      tcp: ecn: dont delay ACKS after CE · aae06bf5
      Eric Dumazet authored
      While playing with CoDel and ECN marking, I discovered a
      non optimal behavior of receiver of CE (Congestion Encountered)
      segments.
      
      In pathological cases, sender has reduced its cwnd to low values,
      and receiver delays its ACK (by 40 ms).
      
      While RFC 3168 6.1.3 (The TCP Receiver) doesn't explicitly recommend
      to send immediate ACKS, we believe its better to not delay ACKS, because
      a CE segment should give same signal than a dropped segment, and its
      quite important to reduce RTT to give ECE/CWR signals as fast as
      possible.
      
      Note we already call tcp_enter_quickack_mode() from TCP_ECN_check_ce()
      if we receive a retransmit, for the same reason.
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Cc: Neal Cardwell <ncardwell@google.com>
      Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      aae06bf5
    • Eric Dumazet's avatar
      net: tcp: GRO should be ECN friendly · a9e050f4
      Eric Dumazet authored
      While doing TCP ECN tests, I discovered GRO was reordering packets if it
      receives one packet with CE set, while previous packets in same NAPI run
      have ECT(0) for the same flow :
      
      09:25:25.857620 IP (tos 0x2,ECT(0), ttl 64, id 27893, offset 0, flags
      [DF], proto TCP (6), length 4396)
          172.30.42.19.54550 > 172.30.42.13.44139: Flags [.], seq
      233801:238145, ack 1, win 115, options [nop,nop,TS val 3397779 ecr
      1990627], length 4344
      
      09:25:25.857626 IP (tos 0x3,CE, ttl 64, id 27892, offset 0, flags [DF],
      proto TCP (6), length 1500)
          172.30.42.19.54550 > 172.30.42.13.44139: Flags [.], seq
      232353:233801, ack 1, win 115, options [nop,nop,TS val 3397779 ecr
      1990627], length 1448
      
      09:25:25.857638 IP (tos 0x0, ttl 64, id 34581, offset 0, flags [DF],
      proto TCP (6), length 64)
          172.30.42.13.44139 > 172.30.42.19.54550: Flags [.], cksum 0xac8f
      (incorrect -> 0xca69), ack 232353, win 1271, options [nop,nop,TS val
      1990627 ecr 3397779,nop,nop,sack 1 {233801:238145}], length 0
      
      We have two problems here :
      
      1) GRO reorders packets
      
        If NIC gave packet1, then packet2, which happen to be from "different
      flows"  GRO feeds stack with packet2, then packet1. I have yet to
      understand how to solve this problem.
      
      2) GRO is not ECN friendly
      
      Delivering packets out of order makes TCP stack not as fast as it could
      be.
      
      In this patch I suggest we make the tos test not part of the 'same_flow'
      determination, but part of the 'should flush' logic
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Cc: Herbert Xu <herbert@gondor.apana.org.au>
      Acked-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a9e050f4
    • Eric Dumazet's avatar
      net: reorganize IP MIB values · 14a19680
      Eric Dumazet authored
      Reduce IP latencies by placing hot MIB IP fields in a single cache line.
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      14a19680
    • Eric Dumazet's avatar
      net: avoid reloads in SNMP_UPD_PO_STATS · d25398df
      Eric Dumazet authored
      Avoid two instructions to reload dev->nd_net->mib.ip_statistics pointer,
      unsing a temp variable, in ip_rcv(), ip_output() paths for example.
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d25398df
  5. 04 Aug, 2012 13 commits
  6. 03 Aug, 2012 8 commits
  7. 02 Aug, 2012 2 commits