1 How the new TCP output machine [nyi] works.
2
3
4 Data is kept on a single queue. The skb->users flag tells us if the frame is
5 one that has been queued already. To add a frame we throw it on the end. Ack
6 walks down the list from the start.
7
8 We keep a set of control flags
9
10
11 sk->tcp_pend_event
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13 TCP_PEND_ACK Ack needed
14 TCP_ACK_NOW Needed now
15 TCP_WINDOW Window update check
16 TCP_WINZERO Zero probing
17
18
19 sk->transmit_queue The transmission frame begin
20 sk->transmit_new First new frame pointer
21 sk->transmit_end Where to add frames
22
23 sk->tcp_last_tx_ack Last ack seen
24 sk->tcp_dup_ack Dup ack count for fast retransmit
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26
27 Frames are queued for output by tcp_write. We do our best to send the frames
28 off immediately if possible, but otherwise queue and compute the body
29 checksum in the copy.
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31 When a write is done we try to clear any pending events and piggy back them.
32 If the window is full we queue full sized frames. On the first timeout in
33 zero window we split this.
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35 On a timer we walk the retransmit list to send any retransmits, update the
36 backoff timers etc. A change of route table stamp causes a change of header
37 and recompute. We add any new tcp level headers and refinish the checksum
38 before sending.
39
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