From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-x236.google.com (mail-la0-x236.google.com [IPv6:2a00:1450:4010:c03::236]) (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 D31EA21F214 for ; Sun, 12 Apr 2015 16:22:47 -0700 (PDT) Received: by labbd9 with SMTP id bd9so45535812lab.2 for ; Sun, 12 Apr 2015 16:22:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=content-type:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=tOOTIHKwws+hHiBfcEc6I9jv6dOI3UnZFWHA5NcWkbg=; b=rpDBsjfjt1E2eBWMLlXEYtPw3C1J76VFKA16Nb2eRaPwo8AfMgjoOuOrucwmtniOuI oov4+6SzVSBj1i7jpzzmVaaLGaoK3PLcyhIhR1slm+ApZ1ujmOCj0rDtoKf7VgBZymuK BPCa4MOAlTFBPZSkd1s6OnS31svEQHN2QNsKYWtj+0e6EN3Wig0HkANu4m68nsiOOWss HvRKa1zKkmhEvOzKyqEdTyTbRZaHGOd6Km8EaUgJ0kWktXFPiaFWH2fV+3B2KYyhpv32 +m9GkHyCOxyHW4kIS/MqiXje+jiZtE5z6Tdpvx8loFdHR35MEe9fDevNcx88wSi/ATaa jgDw== X-Received: by 10.112.211.134 with SMTP id nc6mr10638153lbc.52.1428880965460; Sun, 12 Apr 2015 16:22:45 -0700 (PDT) Received: from bass.home.chromatix.fi (87-93-27-145.bb.dnainternet.fi. [87.93.27.145]) by mx.google.com with ESMTPSA id 7sm1269073lax.44.2015.04.12.16.22.43 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 12 Apr 2015 16:22:44 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) From: Jonathan Morton In-Reply-To: Date: Mon, 13 Apr 2015 02:22:39 +0300 Content-Transfer-Encoding: quoted-printable Message-Id: <724E2B43-29E4-4344-A910-F41A59ECDF6B@gmail.com> References: To: Dave Taht X-Mailer: Apple Mail (2.2098) Cc: cake@lists.bufferbloat.net Subject: Re: [Cake] Other codel decay issues X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Apr 2015 23:23:16 -0000 > On 13 Apr, 2015, at 01:14, Dave Taht wrote: >=20 > Codel state variable decay is an issue. I did not poke > into the 8 way set associative cache worked, but... >=20 > Queues empty and fill at lower rates as well, you DO > want to reuse the codel queue that was going into in > that case. >=20 > Eric settled on about 3 seconds to gc sch_fq; most > codel versions reset their state at 1600ms empty. >=20 > You probably want a "fresh" codel queue for each new > flow, or one borrowing from other existing states. I took this into account with the set-associative hash design. The function deliberately tries to keep the same flow in the same queue = as much as is reasonable, without flip-flopping a given queue between = flows. The latter is only likely to occur if both flows are fairly = sparse, giving Codel little to do on them, or if severe overload is = causing collisions. To help with testing this, I note that the first version of cake was = functionally equivalent to fq_codel if you specified =E2=80=9Cunlimited = besteffort=E2=80=9D as its options. Cake3 behaves similarly in this = respect, except that now you get the set-associative hash instead of the = plain one (and there=E2=80=99s no way to turn that off at runtime). - Jonathan Morton