Merge branch 'tcp-change-pingpong-to-3-in-delayed-ack-logic'

Wei Wang says:

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tcp: change pingpong to 3 in delayed ack logic

TCP receiver today tries not to delay the ACKs to speed up the initial
slow start (a.k.a QUICK ACK mechanism). However the previous design
does not work well with modern TCP applications that starts with an
application-level handshake. For example, a HTTPs server often
receives the SSL hello and responds right away which triggers the TCP
stack to stop the quick ack and start delaying the ACKs based only one
instance of ping-pong. This patchset changes the threshold from 1 to 3
ping-pong transactions, so that we only start to delay the acks after
the receiver responds data quickly three times.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>