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    [TCP]: Move to new TSO segmenting scheme. · c1b4a7e6
    David S. Miller 提交于
    Make TSO segment transmit size decisions at send time not earlier.
    
    The basic scheme is that we try to build as large a TSO frame as
    possible when pulling in the user data, but the size of the TSO frame
    output to the card is determined at transmit time.
    
    This is guided by tp->xmit_size_goal.  It is always set to a multiple
    of MSS and tells sendmsg/sendpage how large an SKB to try and build.
    
    Later, tcp_write_xmit() and tcp_push_one() chop up the packet if
    necessary and conditions warrant.  These routines can also decide to
    "defer" in order to wait for more ACKs to arrive and thus allow larger
    TSO frames to be emitted.
    
    A general observation is that TSO elongates the pipe, thus requiring a
    larger congestion window and larger buffering especially at the sender
    side.  Therefore, it is important that applications 1) get a large
    enough socket send buffer (this is accomplished by our dynamic send
    buffer expansion code) 2) do large enough writes.
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    c1b4a7e6
tcp.c 63.0 KB