From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [52.28.52.200]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 61FC73B29E for ; Tue, 17 Apr 2018 09:51:00 -0400 (EDT) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1523973059; bh=fBMT1iq1hbP62U9xE8Mc3qal1AMF3rnlLeu1wyoDLMI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=c9qzHGOIrwRpHVogeMqLJOf97iohcdt/34s/2Q8geQfOFNBVdokFF/Rq1bkV7wSFk daS1E0SJG4rCYoBOHrB12dhYKTzYd5sY01zc4NOyV3ouo7HQ4rjl+SS/3o47Z9fwUp vV8mHyO+6RhMCK7qSzy3YLGU5bW0bbp54qcA6M/tDTcu7RE62dNALn0t46PF62FS4P GLofVPrAuhLNkmUWBwHOGYwRF2gfG7AwYc0SMRO5cFbZhv0A2snQlBNta5XkaLKP8H 6qGhcMp2YzhSyi7nN1+fg2XSceaDr1YyhUKczFVbO3Eu8ypKUueyR39+7yBDwxNk76 3lXlV88O8X7sQ== To: Jonas =?utf-8?Q?M=C3=A5rtensson?= Cc: Y , Cake List In-Reply-To: References: <87vacq419h.fsf@toke.dk> <87sh7u3yoa.fsf@toke.dk> <87muy23tvg.fsf@toke.dk> Date: Tue, 17 Apr 2018 15:50:58 +0200 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <87a7u23prx.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Cake] A few puzzling Cake results X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Apr 2018 13:51:00 -0000 Jonas M=C3=A5rtensson writes: > On Tue, Apr 17, 2018 at 2:22 PM, Toke H=C3=B8iland-J=C3=B8rgensen > wrote: > >> Y via Cake writes: >> >> > From: Y >> > Subject: Re: [Cake] A few puzzling Cake results >> > To: cake@lists.bufferbloat.net >> > Date: Tue, 17 Apr 2018 21:05:12 +0900 >> > >> > Hi. >> > >> > Any certain fomula of fq_codel flow number? >> >> Well, given N active bulk flows with packet size L, and assuming the >> quantum Q=3DL (which is the default for FQ-CoDel at full-size 1500-byte >> packets), the maximum rate for a sparse flow, R_s, is bounded by >> >> R_s < R / ((L/L_s)(N+1)) >> >> Where R is the link rate and L_s is the packet size of the sparse flow. >> This assumes that the sparse flow has constant spacing between its >> packets, which is often the case for a VoIP flow... > > > For 10-Mbit/s link rate and 32 bulk flows with 1500-byte packets this > formula gives roughly 25 pps (packets per second) as maximum for a sparse > flow. A VoIP flow is typically 50 pps (20 ms voice payload). > > Does this mean that cake sets the quantum to less than 750 bytes for a > 10-Mbit/s link? Yup, it sets it to 305 bytes. I added this to the stats output in the latest git version. > Do you see any benefit with cake diffserv if you increase the number > of flows? I have not been able to see a benefit of diffserv mode for the VoIP flow. Even at 128 flows there's no difference; and beyond that my testbed can't keep up anymore... Diffserv mode doesn't hurt either, though... It may simply be that its primary utility is to allow flows to *de*prioritise themselves... > Does the adjusted quantum also explain the "*way* higher" TCP RTT for > cake? How? Nope, don't think so. I think the difference in TCP RTT is due to differences in the CoDel implementation. -Toke