Re: [quicwg/base-drafts] MinRTT for the path (#2919)
Jana Iyengar <notifications@github.com> Mon, 13 January 2020 21:32 UTC
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Subject: Re: [quicwg/base-drafts] MinRTT for the path (#2919)
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janaiyengar commented on this pull request. s/path/network path > @@ -249,11 +249,10 @@ more accurate round-trip time estimate (see Section 13.2 of {{QUIC-TRANSPORT}}). At a high level, an endpoint measures the time from when a packet was sent to when it is acknowledged as a round-trip time (RTT) sample. The endpoint uses RTT samples and peer-reported host delays (see Section 13.2 of -{{QUIC-TRANSPORT}}) to generate a statistical description of the connection's -RTT. An endpoint computes the following three values: the minimum value -observed over the lifetime of the connection (min_rtt), an -exponentially-weighted moving average (smoothed_rtt), and the variance in the -observed RTT samples (rttvar). +{{QUIC-TRANSPORT}}) to generate a statistical description of the path's RTT. ```suggestion {{QUIC-TRANSPORT}}) to generate a statistical description of the network path's RTT. ``` > @@ -295,16 +294,22 @@ retain sufficient history is an open research question. ## Estimating min_rtt {#min-rtt} -min_rtt is the minimum RTT observed over the lifetime of the connection. -min_rtt is set to the latest_rtt on the first sample in a connection, and to the -lesser of min_rtt and latest_rtt on subsequent samples. +min_rtt is the minimum RTT observed for a given path. min_rtt is set to the ```suggestion min_rtt is the minimum RTT observed for a given network path. min_rtt is set to the ``` > An endpoint uses only locally observed times in computing the min_rtt and does not adjust for host delays reported by the peer. Doing so allows the endpoint to set a lower bound for the smoothed_rtt based entirely on what it observes (see {{smoothed-rtt}}), and limits potential underestimation due to erroneously-reported delays by the peer. +The RTT for a path may change over time. If a path's actual RTT decreases, ```suggestion The RTT for a network path may change over time. If a path's actual RTT decreases, ``` > @@ -333,11 +338,10 @@ endpoint: min_rtt. This limits the underestimation that a misreporting peer can cause to the smoothed_rtt. -On the first RTT sample in a connection, the smoothed_rtt is set to the -latest_rtt. +On the first RTT sample for a path, the smoothed_rtt is set to the latest_rtt. ```suggestion On the first RTT sample for a network path, the smoothed_rtt is set to the latest_rtt. ``` > smoothed_rtt and rttvar are computed as follows, similar to {{?RFC6298}}. On -the first RTT sample in a connection: +the first RTT sample for a path: ```suggestion the first RTT sample for a network path: ``` > An endpoint uses only locally observed times in computing the min_rtt and does not adjust for host delays reported by the peer. Doing so allows the endpoint to set a lower bound for the smoothed_rtt based entirely on what it observes (see {{smoothed-rtt}}), and limits potential underestimation due to erroneously-reported delays by the peer. +The RTT for a path may change over time. If a path's actual RTT decreases, +the min_rtt will adapt immediately on the first low sample. If the path's ```suggestion the min_rtt will adapt immediately on the first low sample. If the network path's ``` -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/quicwg/base-drafts/pull/2919#pullrequestreview-342152058
- [quicwg/base-drafts] MinRTT for the congestion co… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… Jana Iyengar
- Re: [quicwg/base-drafts] MinRTT for the congestio… Jana Iyengar
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… Eric Kinnear
- Re: [quicwg/base-drafts] MinRTT for the congestio… Martin Thomson
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the congestio… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… Jana Iyengar
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… Jana Iyengar
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett
- Re: [quicwg/base-drafts] MinRTT for the path (#29… ianswett