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Diffstat (limited to 'Documentation/networking/tcp.txt')
| -rw-r--r-- | Documentation/networking/tcp.txt | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/networking/tcp.txt b/Documentation/networking/tcp.txt new file mode 100644 index 00000000000..71749007091 --- /dev/null +++ b/Documentation/networking/tcp.txt @@ -0,0 +1,39 @@ +How the new TCP output machine [nyi] works. + + +Data is kept on a single queue. The skb->users flag tells us if the frame is +one that has been queued already. To add a frame we throw it on the end. Ack +walks down the list from the start. + +We keep a set of control flags + + + sk->tcp_pend_event + + TCP_PEND_ACK Ack needed + TCP_ACK_NOW Needed now + TCP_WINDOW Window update check + TCP_WINZERO Zero probing + + + sk->transmit_queue The transmission frame begin + sk->transmit_new First new frame pointer + sk->transmit_end Where to add frames + + sk->tcp_last_tx_ack Last ack seen + sk->tcp_dup_ack Dup ack count for fast retransmit + + +Frames are queued for output by tcp_write. We do our best to send the frames +off immediately if possible, but otherwise queue and compute the body +checksum in the copy. + +When a write is done we try to clear any pending events and piggy back them. +If the window is full we queue full sized frames. On the first timeout in +zero window we split this. + +On a timer we walk the retransmit list to send any retransmits, update the +backoff timers etc. A change of route table stamp causes a change of header +and recompute. We add any new tcp level headers and refinish the checksum +before sending. + |