[Ecn-sane] cwnd/2 - 1

Dave Taht dave.taht at gmail.com
Fri Sep 7 03:18:48 EDT 2018

One of the things that went by in recent kernel changes was that
linux tcp at a cwnd 2 on a CE goes into quickack mode, so that we
get back one ack per packet (I think, from reading the commit) instead of
every other one.

halving cwnd and then taking off 1 more gives a response that drops the
mass closer along the lines of what a drop may do in response to loss
and re-ordering. A cwnd 1 in quickack mode would halve the number of
packets outstanding in my 100 flows test. I think.

another thing to note is that retransmits, are, by the standard, and
in linux, not protected by ECT, and when you get near to 100% mark
rate as i do in this artificial test, get dropped a lot.


Dave Täht
CEO, TekLibre, LLC
Tel: 1-669-226-2619

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