1. 07 8月, 2017 18 次提交
  2. 05 8月, 2017 18 次提交
  3. 04 8月, 2017 4 次提交
    • W
      tcp: enable MSG_ZEROCOPY · f214f915
      Willem de Bruijn 提交于
      Enable support for MSG_ZEROCOPY to the TCP stack. TSO and GSO are
      both supported. Only data sent to remote destinations is sent without
      copying. Packets looped onto a local destination have their payload
      copied to avoid unbounded latency.
      
      Tested:
        A 10x TCP_STREAM between two hosts showed a reduction in netserver
        process cycles by up to 70%, depending on packet size. Systemwide,
        savings are of course much less pronounced, at up to 20% best case.
      
        msg_zerocopy.sh 4 tcp:
      
        without zerocopy
          tx=121792 (7600 MB) txc=0 zc=n
          rx=60458 (7600 MB)
      
        with zerocopy
          tx=286257 (17863 MB) txc=286257 zc=y
          rx=140022 (17863 MB)
      
        This test opens a pair of sockets over veth, one one calls send with
        64KB and optionally MSG_ZEROCOPY and on the other reads the initial
        bytes. The receiver truncates, so this is strictly an upper bound on
        what is achievable. It is more representative of sending data out of
        a physical NIC (when payload is not touched, either).
      Signed-off-by: NWillem de Bruijn <willemb@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f214f915
    • W
      sock: ulimit on MSG_ZEROCOPY pages · a91dbff5
      Willem de Bruijn 提交于
      Bound the number of pages that a user may pin.
      
      Follow the lead of perf tools to maintain a per-user bound on memory
      locked pages commit 789f90fc ("perf_counter: per user mlock gift")
      Signed-off-by: NWillem de Bruijn <willemb@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a91dbff5
    • W
      sock: MSG_ZEROCOPY notification coalescing · 4ab6c99d
      Willem de Bruijn 提交于
      In the simple case, each sendmsg() call generates data and eventually
      a zerocopy ready notification N, where N indicates the Nth successful
      invocation of sendmsg() with the MSG_ZEROCOPY flag on this socket.
      
      TCP and corked sockets can cause send() calls to append new data to an
      existing sk_buff and, thus, ubuf_info. In that case the notification
      must hold a range. odify ubuf_info to store a inclusive range [N..N+m]
      and add skb_zerocopy_realloc() to optionally extend an existing range.
      
      Also coalesce notifications in this common case: if a notification
      [1, 1] is about to be queued while [0, 0] is the queue tail, just modify
      the head of the queue to read [0, 1].
      
      Coalescing is limited to a few TSO frames worth of data to bound
      notification latency.
      Signed-off-by: NWillem de Bruijn <willemb@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      4ab6c99d
    • W
      sock: enable MSG_ZEROCOPY · 1f8b977a
      Willem de Bruijn 提交于
      Prepare the datapath for refcounted ubuf_info. Clone ubuf_info with
      skb_zerocopy_clone() wherever needed due to skb split, merge, resize
      or clone.
      
      Split skb_orphan_frags into two variants. The split, merge, .. paths
      support reference counted zerocopy buffers, so do not do a deep copy.
      Add skb_orphan_frags_rx for paths that may loop packets to receive
      sockets. That is not allowed, as it may cause unbounded latency.
      Deep copy all zerocopy copy buffers, ref-counted or not, in this path.
      
      The exact locations to modify were chosen by exhaustively searching
      through all code that might modify skb_frag references and/or the
      the SKBTX_DEV_ZEROCOPY tx_flags bit.
      
      The changes err on the safe side, in two ways.
      
      (1) legacy ubuf_info paths virtio and tap are not modified. They keep
          a 1:1 ubuf_info to sk_buff relationship. Calls to skb_orphan_frags
          still call skb_copy_ubufs and thus copy frags in this case.
      
      (2) not all copies deep in the stack are addressed yet. skb_shift,
          skb_split and skb_try_coalesce can be refined to avoid copying.
          These are not in the hot path and this patch is hairy enough as
          is, so that is left for future refinement.
      Signed-off-by: NWillem de Bruijn <willemb@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1f8b977a