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  1. Apr 27, 2018
    • Willem de Bruijn's avatar
      udp: generate gso with UDP_SEGMENT · bec1f6f6
      Willem de Bruijn authored
      Support generic segmentation offload for udp datagrams. Callers can
      concatenate and send at once the payload of multiple datagrams with
      the same destination.
      
      To set segment size, the caller sets socket option UDP_SEGMENT to the
      length of each discrete payload. This value must be smaller than or
      equal to the relevant MTU.
      
      A follow-up patch adds cmsg UDP_SEGMENT to specify segment size on a
      per send call basis.
      
      Total byte length may then exceed MTU. If not an exact multiple of
      segment size, the last segment will be shorter.
      
      The implementation adds a gso_size field to the udp socket, ip(v6)
      cmsg cookie and inet_cork structure to be able to set the value at
      setsockopt or cmsg time and to work with both lockless and corked
      paths.
      
      Initial benchmark numbers show UDP GSO about as expensive as TCP GSO.
      
          tcp tso
           3197 MB/s 54232 msg/s 54232 calls/s
               6,457,754,262      cycles
      
          tcp gso
           1765 MB/s 29939 msg/s 29939 calls/s
              11,203,021,806      cycles
      
          tcp without tso/gso *
            739 MB/s 12548 msg/s 12548 calls/s
              11,205,483,630      cycles
      
          udp
            876 MB/s 14873 msg/s 624666 calls/s
              11,205,777,429      cycles
      
          udp gso
           2139 MB/s 36282 msg/s 36282 calls/s
              11,204,374,561      cycles
      
         [*] after reverting commit 0a6b2a1d
      
      
             ("tcp: switch to GSO being always on")
      
      Measured total system cycles ('-a') for one core while pinning both
      the network receive path and benchmark process to that core:
      
        perf stat -a -C 12 -e cycles \
          ./udpgso_bench_tx -C 12 -4 -D "$DST" -l 4
      
      Note the reduction in calls/s with GSO. Bytes per syscall drops
      increases from 1470 to 61818.
      
      Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      bec1f6f6
    • Willem de Bruijn's avatar
      udp: add udp gso · ee80d1eb
      Willem de Bruijn authored
      
      
      Implement generic segmentation offload support for udp datagrams. A
      follow-up patch adds support to the protocol stack to generate such
      packets.
      
      UDP GSO is not UFO. UFO fragments a single large datagram. GSO splits
      a large payload into a number of discrete UDP datagrams.
      
      The implementation adds a GSO type SKB_UDP_GSO_L4 to differentiate it
      from UFO (SKB_UDP_GSO).
      
      IPPROTO_UDPLITE is excluded, as that protocol has no gso handler
      registered.
      
      [ Export __udp_gso_segment for ipv6. -DaveM ]
      
      Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      ee80d1eb
    • Willem de Bruijn's avatar
      udp: expose inet cork to udp · 1cd7884d
      Willem de Bruijn authored
      
      
      UDP segmentation offload needs access to inet_cork in the udp layer.
      Pass the struct to ip(6)_make_skb instead of allocating it on the
      stack in that function itself.
      
      This patch is a noop otherwise.
      
      Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      1cd7884d
  2. Apr 26, 2018
  3. Apr 25, 2018