Date: Thu, 23 Jan 2020 01:46:11 -0800
From: mirjak <notifications@github.com>
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Message-ID: <quicwg/base-drafts/pull/3384/review/347167245@github.com>
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Subject: Re: [quicwg/base-drafts] !editorial: simplify pseudo code (recovery)
 (#3384)
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mirjak commented on this pull request.



> @@ -346,9 +346,7 @@ On subsequent RTT samples, smoothed_rtt and rttvar evolve as follows:
 
 ~~~
 ack_delay = min(Ack Delay in ACK Frame, max_ack_delay)
-adjusted_rtt = latest_rtt
-if (min_rtt + ack_delay < latest_rtt):
-  adjusted_rtt = latest_rtt - ack_delay
+adjusted_rtt = max(latest_rtt - ack_delay, min_rtt)

Ups, yes, you are right. I think I got that impression from reading "MUST NOT apply the adjustment if the resulting RTT sample is smaller than the min_rtt", however, that's not what it says.

I think changing the if to the following would be slightly more readable for me but doesn't make a big difference:

if (latest_rtt - ack_delay > min_rtt):

Or even

 adjusted_rtt = latest_rtt  - ack_delay
 if (adjusted_rtt > min_rtt):
   adjusted_rtt = latest_rtt

However, we can also just withdraw this PR.

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<p><b>@mirjak</b> commented on this pull request.</p>

<hr>

<p>In <a href="https://github.com/quicwg/base-drafts/pull/3384#discussion_r370017839">draft-ietf-quic-recovery.md</a>:</p>
<pre style='color:#555'>&gt; @@ -346,9 +346,7 @@ On subsequent RTT samples, smoothed_rtt and rttvar evolve as follows:
 
 ~~~
 ack_delay = min(Ack Delay in ACK Frame, max_ack_delay)
-adjusted_rtt = latest_rtt
-if (min_rtt + ack_delay &lt; latest_rtt):
-  adjusted_rtt = latest_rtt - ack_delay
+adjusted_rtt = max(latest_rtt - ack_delay, min_rtt)
</pre>
<p>Ups, yes, you are right. I think I got that impression from reading "MUST NOT apply the adjustment if the resulting RTT sample is smaller than the min_rtt", however, that's not what it says.</p>
<p>I think changing the if to the following would be slightly more readable for me but doesn't make a big difference:</p>
<p>if (latest_rtt - ack_delay &gt; min_rtt):</p>
<p>Or even</p>
<p>adjusted_rtt = latest_rtt  - ack_delay<br>
if (adjusted_rtt &gt; min_rtt):<br>
adjusted_rtt = latest_rtt</p>
<p>However, we can also just withdraw this PR.</p>

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