aboutsummaryrefslogtreecommitdiff
path: root/Documentation/networking/tcp.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/networking/tcp.txt')
-rw-r--r--Documentation/networking/tcp.txt39
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.
+