Re: [quicwg/base-drafts] Remove ack_delay_exponent TP (#2670)

Kazuho Oku <> Thu, 13 June 2019 02:15 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id C26E012006A for <>; Wed, 12 Jun 2019 19:15:20 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -8.008
X-Spam-Status: No, score=-8.008 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_IMAGE_ONLY_32=0.001, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_DKIMWL_WL_HIGH=-0.01] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id HJ_ticaaJJbn for <>; Wed, 12 Jun 2019 19:15:19 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id D9FBA12004A for <>; Wed, 12 Jun 2019 19:15:18 -0700 (PDT)
Date: Wed, 12 Jun 2019 19:15:17 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1560392117; bh=maI7vpwS2odHPndMFjyviB5rdFMuYetgNp+ertiAB1g=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=1q8/LxpCRExav9bEp8HDg1oolr4BwV5muhbmwo9Epa5YyJW+3ecemWVCgiEHK6t+f cnnCt7QBXs5zWYdeBvzZsYykwlvpULrrRPKfrOq9UNromSWKNo1T4xX1M3AfpWzfyV k6kh33lR58JbXD1jbTXe4uFcT46d7Rblf+wp5zG4=
From: Kazuho Oku <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/issues/2670/>
In-Reply-To: <quicwg/base-drafts/issues/>
References: <quicwg/base-drafts/issues/>
Subject: Re: [quicwg/base-drafts] Remove ack_delay_exponent TP (#2670)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5d01b1b5aa34d_38f93f877d0cd96c29301a"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: kazuho
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
Archived-At: <>
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 13 Jun 2019 02:15:21 -0000

Unsurprisingly, I prefer _b_ (multiplication), and the reason is as follows.

As @huitema points out, the computational cost of using a multiplier is no worse than using an exponent, and I second @marten-seemann's comment that use of exponent is strictly worse than using a multiplier. I do not think there is a justifiable reason to choose _a_ (exponent).

The network overhead of using no scaling factor would be 2 to 3 bytes per packet that contains an ACK, for the primary use-case of QUIC v1 traffic. This is because we can assume that connections between web browsers and servers would be in most cases greater than 16.383 milliseconds.

Considering the effort we have spent in reducing the number of bytes being transmitted on the wire, I think it might make more sense to have a multiplier than removing the scaling factor.

You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub: