Re: [quicwg/base-drafts] ACK generation recommendation (#3304)

ianswett <notifications@github.com> Thu, 19 December 2019 15:54 UTC

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Subject: Re: [quicwg/base-drafts] ACK generation recommendation (#3304)
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@janaiyengar In terms of 'how bad was 1/8RTT with Cubic', I can't find any results, only results for 1/4 RTT.  1/8RTT was an option added after 1/4RTT was tested and showed a clear regression, so possibly it was never tested with Cubic.  That was around the time BBR was being developed, so I think the focus was on BBR.

If we head in the direction of recommending a fixed fraction, I'll need to re-run those experiments with Cubic to quantify the regression.

I'll note the way Chrome implements 1/4 and 1/8RTT ACK decimation means it takes the min of max_ack_delay and the RTT fraction, so in some cases receivers will send more ACKs for a given max_ack_delay.
https://cs.chromium.org/chromium/src/net/third_party/quiche/src/quic/core/quic_received_packet_manager.cc?sq=package:chromium&g=0&l=246

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