From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-x22a.google.com (mail-yk0-x22a.google.com [IPv6:2607:f8b0:4002:c07::22a]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id DB3ED21F9BB for ; Tue, 11 Aug 2015 12:13:32 -0700 (PDT) Received: by ykdz80 with SMTP id z80so63956283ykd.2 for ; Tue, 11 Aug 2015 12:13:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=udVal4mId79yMM3dJRgPrYu2f+fC1A04ASQx/pm+BLE=; b=ZrImOkN2JC6oM+JLWixnOQVkViT44bP5w7weaHxZVrwY9FIwPMDRWAbJiAy9NvpmUQ bevwFSjoWUSXLbeNDxY+llQ3SdG/K5+7cb/eXANhVCbdO5Mo1OniqFqCemBjDdx8IGno m+QonipaO6Tkbk7FsxD67R1CJUkJB5nfYx4oUspeD5hGX6g1A7BP89vscBr9XsEZfR1r DnrQOlxyJCxlbMmCayqqygzo5x6O43iE8vh5x5NiLM/vsVsJ3gGKc2GsBAiDTWP7lUk0 tJKW5off6Lv57SbvTQGYN0lP0oevTxyedbMUtOjlmOpZSq5rzq8j2ZBWrx40Jp+J5Xzt Eg/g== MIME-Version: 1.0 X-Received: by 10.129.97.135 with SMTP id v129mr18687904ywb.78.1439320411743; Tue, 11 Aug 2015 12:13:31 -0700 (PDT) Received: by 10.37.214.203 with HTTP; Tue, 11 Aug 2015 12:13:31 -0700 (PDT) Received: by 10.37.214.203 with HTTP; Tue, 11 Aug 2015 12:13:31 -0700 (PDT) In-Reply-To: <274D3A0FA900FD47AA6B56991AAA32FDC53BB5B1@wtl-exchp-1.sandvine.com> References: <274D3A0FA900FD47AA6B56991AAA32FDC53BB45E@wtl-exchp-1.sandvine.com> <274D3A0FA900FD47AA6B56991AAA32FDC53BB5B1@wtl-exchp-1.sandvine.com> Date: Tue, 11 Aug 2015 22:13:31 +0300 Message-ID: From: Jonathan Morton To: Jeff Weeks Content-Type: multipart/alternative; boundary=001a11490c1edc2b1d051d0de5eb Cc: codel@lists.bufferbloat.net Subject: Re: [Codel] drop state short-circuit... X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 11 Aug 2015 19:14:01 -0000 --001a11490c1edc2b1d051d0de5eb Content-Type: text/plain; charset=UTF-8 That would imply an unresponsive flow (or a large aggregation of flows in one queue, which would require a high drop rate to respond). Indeed, the Codel algorithm in itself doesn't guarantee any latency bound. Only a hard limit on queue length can do that (or forcibly dropping packets with sojourn times above the limit). Practical qdisc implementations do have such mechanisms. Flow isolation helps in such circumstances, especially if the qdisc drops from the longest queue on enqueue overflow. - Jonathan Morton --001a11490c1edc2b1d051d0de5eb Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

That would imply an unresponsive flow (or a large aggregatio= n of flows in one queue, which would require a high drop rate to respond).<= /p>

Indeed, the Codel algorithm in itself doesn't guarantee = any latency bound.=C2=A0 Only a hard limit on queue length can do that (or = forcibly dropping packets with sojourn times above the limit).=C2=A0 Practi= cal qdisc implementations do have such mechanisms.

Flow isolation helps in such circumstances, especially if th= e qdisc drops from the longest queue on enqueue overflow.

- Jonathan Morton

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