The basic problem, as I've written before[1][2], is that, after I put in Nagle's algorithm, Berkeley put in delayed ACKs. Delayed ACKs delay sending an empty ACK packet for a short, fixed period based on human typing speed, maybe 100ms. This was a hack Berkeley put in to handle large numbers of dumb terminals going in to time-sharing computers using terminal to Ethernet concentrators. Without delayed ACKs, each keystroke sent a datagram with one payload byte, and got a datagram back with no payload, just an ACK, followed shortly thereafter by a datagram with one echoed character. So they got a 30% load reduction for their TELNET application.
Both of those algorithms should never be on at the same time. But they usually are.
Linux has a socket option, TCP_QUICKACK, to turn off delayed ACKs. But it's very strange. The documentation is kind of vague, but apparently you have to re-enable it regularly.[3]
Sigh.
[1] https://news.ycombinator.com/item?id=10608356
[2] https://developers.slashdot.org/comments.pl?cid=14515105&sid...
[3] https://stackoverflow.com/questions/46587168/when-during-the...
Both of those algorithms should never be on at the same time. But they usually are.
Linux has a socket option, TCP_QUICKACK, to turn off delayed ACKs. But it's very strange. The documentation is kind of vague, but apparently you have to re-enable it regularly.[3]
Sigh.
[1] https://news.ycombinator.com/item?id=10608356
[2] https://developers.slashdot.org/comments.pl?cid=14515105&sid...
[3] https://stackoverflow.com/questions/46587168/when-during-the...