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Re: [quicwg/base-drafts] QUIC PTO is too conservative, causing a measurable regression in tail latency (#3526)

ianswett <notifications@github.com> Sat, 21 March 2020 21:18 UTC

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Date: Sat, 21 Mar 2020 14:18:07 -0700
From: ianswett <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] QUIC PTO is too conservative, causing a measurable regression in tail latency (#3526)
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@martinthomson Everything you said makes sense to me.  I'm hoping to come up with a proposal that does 2 things:
1) Is not a regression for our current gQUIC implementation (or TCP best practices)
2) Build on well publicized and accepted concepts from TCP(ie: TLP and RTO)
3) Reduce the rate of spurious retransmits vs gQUIC.

In terms of RTTVar vs an EWMA'd Stdev, I suspect the end result may be something like: SRTT+4*RTTVar OR SRTT + 2(or 3)*EWMA_Stdev, but I don't have enough data to know for sure yet.  The experiments have been started, so hopefully I should know more in 2 weeks.

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