Re: [quicwg/base-drafts] MinRTT for the congestion control context (#2919)
Jana Iyengar <notifications@github.com> Sun, 21 July 2019 20:17 UTC
Return-Path: <noreply@github.com>
X-Original-To: quic-issues@ietfa.amsl.com
Delivered-To: quic-issues@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id EBD53120193 for <quic-issues@ietfa.amsl.com>; Sun, 21 Jul 2019 13:17:40 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8
X-Spam-Level:
X-Spam-Status: No, score=-8 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=github.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rX59WLAIf8tA for <quic-issues@ietfa.amsl.com>; Sun, 21 Jul 2019 13:17:38 -0700 (PDT)
Received: from out-9.smtp.github.com (out-9.smtp.github.com [192.30.254.192]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 3F34A1200B9 for <quic-issues@ietf.org>; Sun, 21 Jul 2019 13:17:38 -0700 (PDT)
Date: Sun, 21 Jul 2019 13:17:37 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1563740257; bh=q+EhtQt5psQRey4IbRS3MPHVC2Ywxv7G7Z69ROW6Q+g=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=xuxRUrpRFm64MlP60DpQzXzVbfA81faVdzaq2h6WKenkvlq5M8KQ4v3LQVXWpm1jY 49repTZlu+tAuumK3ETQnf5/cLUQrg+BQ9geiImW9prmpUOjk3uFB7GwqtvKtxy6gz Luk7Qp7567ONyKHKvwh+0Yzc2bh2rBPyXSWowdew=
From: Jana Iyengar <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJK2KEM4K5INDCHKL6U53IH5ODEVBNHHBYEA2AU@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/pull/2919/review/264552498@github.com>
In-Reply-To: <quicwg/base-drafts/pull/2919@github.com>
References: <quicwg/base-drafts/pull/2919@github.com>
Subject: Re: [quicwg/base-drafts] MinRTT for the congestion control context (#2919)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5d34c861726f7_3aa53fc570ccd95c89813e"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: janaiyengar
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
X-GitHub-Recipient-Address: quic-issues@ietf.org
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic-issues/p3FlL9BYsP3l1vOplWNqNg5vWHM>
X-BeenThere: quic-issues@ietf.org
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <quic-issues.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic-issues/>
List-Post: <mailto:quic-issues@ietf.org>
List-Help: <mailto:quic-issues-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 21 Jul 2019 20:17:48 -0000
janaiyengar commented on this pull request. > @@ -371,16 +371,23 @@ 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 congestion control context. min_rtt is only used for loss recovery in this doc. I think it's more appropriate to say RTT estimator context in general. > @@ -371,16 +371,23 @@ 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 congestion control context. +min_rtt is set to the latest_rtt on the first RTT sample, and to the lesser +of min_rtt and latest_rtt on subsequent samples. min_rtt is used to reject +implausible RTT samples, but is not used directly in congestion control or I would drop the rest of the text after "samples" and perhaps add "which would otherwise cause the smoothed_rtt estimate to be incorrectly low.". I understand what you're trying to say, but I think saying that it is not used directly in loss recovery makes it a bit confusing I think. It is used, and I think people will have different reads on what's indirect and what's > An endpoint uses only locally observed times in computing the min_rtt and does not adjust for host delays reported by the peer ({{host-delay}}). 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 the path may change over time. If the real path RTT decreases, ```suggestion The RTT for a path may change over time. If a path's actual RTT decreases, ``` > An endpoint uses only locally observed times in computing the min_rtt and does not adjust for host delays reported by the peer ({{host-delay}}). 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 the path may change over time. If the real path RTT decreases, +it should be observed quickly. If the real path RTT increases, it will not ```suggestion the min_rtt will adapt immediately on the first low sample. If the path's actual RTT increases, ``` > An endpoint uses only locally observed times in computing the min_rtt and does not adjust for host delays reported by the peer ({{host-delay}}). 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 the path may change over time. If the real path RTT decreases, +it should be observed quickly. If the real path RTT increases, it will not +be observed, but the impact is limited to allowing some RTT samples that are ```suggestion the min_rtt will not adapt to it, potentially causing future RTT samples that are ``` > @@ -410,11 +417,11 @@ 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 in a congestion control context, the smoothed_rtt is RTT context > smoothed_rtt and rttvar are computed as follows, similar to {{?RFC6298}}. On -the first RTT sample in a connection: +the first RTT sample in a congestion control context: RTT context -- 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-264552498
- [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