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net/tcp: Minor design improvement to TCP delayed ACKs.

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This commit is contained in:
Gregory Nutt 2019-12-08 14:17:55 -06:00
parent 66ef6d143a
commit 8cd5e04d53
1 changed files with 9 additions and 12 deletions
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21
net/tcp/tcp_appsend.c
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@ -101,9 +101,13 @@ void tcp_appsend(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
/* Per RFC 1122: "...there SHOULD be an ACK for at least every second
* segment."
*
* NOTE: If there is a data payload or other flags to be sent with the
* outgoing packet, then we may as well include the ACK too.
*/
if (conn->rx_unackseg > 0)
if (conn->rx_unackseg > 0 || dev->d_sndlen > 0 ||
result != TCP_SNDACK)
{
/* Reset the delayed ACK state and send the ACK with this packet. */
@ -111,20 +115,13 @@ void tcp_appsend(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
}
else
{
/* Indicate that there is one un-ACKed segment and don't send the
* ACK on this pack.
/* This is only an ACK and there is no pending delayed ACK and
* no TX data is being sent. Indicate that there is one un-ACKed
* segment and don't send anything now.
*/
result &= ~TCP_SNDACK;
conn->rx_unackseg = 1;
/* A special case is if there are not other flags and no TCP TX
* data payload. In this case, don't send anything.*/
if (result == 0 && dev->d_sndlen == 0)
{
return;
}
return;
}
}
#endif