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Re: [quicwg/base-drafts] Simplify TLP and RTO into Probe Timeout (#2114)

Subodh Iyengar <notifications@github.com> Tue, 11 December 2018 21:11 UTC

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Subject: Re: [quicwg/base-drafts] Simplify TLP and RTO into Probe Timeout (#2114)
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siyengar commented on this pull request.



> @@ -726,10 +700,9 @@ Pseudocode for OnAckReceived and UpdateRtt follow:
       // RTO was spurious. Otherwise, inform congestion control.
       if (rto_count > 0 &&
             smallest_newly_acked > largest_sent_before_rto):

largest_sent_before_rto is still used here

>  
 ~~~
-   OnRetransmissionTimeoutVerified(packet_number)
+   OnProbeTimeoutVerified(packet_number)

This looks like we will set the probetimeout verified even if this happens

    1, 2, 3 [lost], 4 [probe], 5 [probe]
    -> [ack 4]
    -> cwnd = mincwnd

in the first probe case it seems like the probe would be aggressive so it would be bad to drop the cwnd down.

even if it not aggressive right now, in the future I think we are going to tune timeouts constant per application (realtime vs interactive). This means that if we tune timeout constants too aggressively, it will result in having this reaction.

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