From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id A484A3B2A4 for ; Fri, 1 Dec 2017 03:45:55 -0500 (EST) Received: from [192.168.250.101] ([134.76.241.253]) by mail.gmx.com (mrgmx002 [212.227.17.190]) with ESMTPSA (Nemesis) id 0MdrK9-1ejlwa239p-00PhRo; Fri, 01 Dec 2017 09:45:45 +0100 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) From: Sebastian Moeller In-Reply-To: Date: Fri, 1 Dec 2017 09:45:42 +0100 Cc: Mikael Abrahamsson , bloat Content-Transfer-Encoding: quoted-printable Message-Id: <401BE104-CFCC-449C-9904-A7C118B869E2@gmx.de> References: <4D0E907C-E15D-437C-B6F7-FF348346D615@gmx.de> <7B92DF4D-B6B5-4A64-9E10-119DCA2D4A6F@ifi.uio.no> <1512037480.19682.10.camel@gmail.com> To: David Lang X-Mailer: Apple Mail (2.3273) X-Provags-ID: V03:K0:DWUVOx8NsEF4t9bkIGGo6k72eG1tfIkBZLiwm4rTTi01JB42ZPE GO4+VwQC4ZCf/oGf8ozR9EFjtb1WzBnUdNWwrODrDasIcf5ljavaKXHJAccNpSLDM9jebXi cshbiip5s5pRNzT4iU02whYz8TwAWzb2u9YjdLKh5ecQJqaJHr+rx+g601SgocFlOS+qgYO wKx7+tSmNYhffHc7a3I8A== X-UI-Out-Filterresults: notjunk:1;V01:K0:K6rGrqPu5eg=:h5krv58sdR9GjvU1YHft3E pOf827ABaqI7j8lChXORyOdO0XAcM933hf5XeA7UanOT3T85VNHtvM9CmNhiY3bLQrNySp/tp 9+sTsTuHnXlYDV8hUAg9ccQoZ0zC0ja+8mhatJVRN1dqm/m5AtIGpNUX0GUjFJIsTHj82coDJ zT/HLXFxSMD+b+yQhz5CpL8EGYiaHsQB6B3jJsL+KzeMq73PFIlTNk9eV7EZ1RQE8G9V4jTdi n8iONY8OjNIyaFJvUSymY6RLK/J5ywrhRRkYZyas/MOcuRYdnmq+eJfiJvrt2+IvRbBOaS08I jHfdGPwN0e2go95GtvHLNDIGXY+0Gl5HtVgI6y4ddFWTQEiJICJXtnFji6vbsgXax+yx7VAfM 3HzeNZoeAVcVwlth0bQwTcpUld/amYCAn/fUi8bq1/RcniHITyBvfxsvMqKIqcijqkgXweFQM reBKLnnpSKNnCXviz6iT0uu9qP8xNqgDWS/m9CdMU6dVB9OHrE29HWfo3KChpm3CS97gDS12d iDc/G4ZBJ90GVaFgyckeyXu16J+tD36NFFfjvRkd4DO1Q3T2H4U4dg4qxHSI4QVBxEr+2Ru4i HyztpErDPVqqPQqUI0ZJsztH/AKbsLdG2u7ME9XLaT4jxVnpsukPjo9j9ShcZepDmtbo4pomW ZUGf9wN4MN34rLPNDsNwH5wzCVI0qXXA0wUbfWPX7e2+M/qCKsdsgxvEl4hQEf1++BGCTMM6u W9uIqQVpvLedncAovVy24uTxPrKfGkJWQA8OB6hLDVCWmIMg6XJXtdW71pKdJSbfTeLCJ12l1 E99N3MWiRYjl352owv5m1vjFLAS58+slMK4MLTO+vYe34jrrKg= Subject: Re: [Bloat] benefits of ack filtering X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Dec 2017 08:45:56 -0000 Hi All, you do realize that the worst case is going to stay at 35KPPS? If we = assume simply that the 100Mbps download rate is not created by a single = flow but by many flows (say 70K flows) the discussed ACK frequency = reduction schemes will not work that well. So ACK thinning is a nice = optimization, but will not help the fact that some ISPs/link = technologies simply are asymmetric and the user will suffer under some = traffic conditions. Now the 70K flow example is too extreme, but the = fact is at hight flow number with sparse flows (so fewer ACKs per flow = in the queue and fewer ACKs per flow reaching the end NIC in a = GRO-collection interval (I naively assume there is a somewhat fixed but = small interval in which packets of the same flow are collected for GRO)) = there will be problems. (Again, I am all for allowing the end user to = configure ACK filtering thinning, but I would rather see ISPs sell less = imbalanced links ;) ) Best Regards Sebastian > On Dec 1, 2017, at 01:28, David Lang wrote: >=20 > 35K PPS of acks is insane, one ack every ms is FAR more than enough to = do 'fast recovery', and outside the datacenter, one ack per 10ms is = probably more than enough. >=20 > Assuming something that's not too assymetric, thinning out the acks = may not make any difference in the transfer rate of a single data flow = in one direction, but if you step back and realize that there may be a = need to transfer data in the other direction, things change here. >=20 > If you have a fully symmetrical link, and are maxing it out in both = direction, going from 35K PPs of aks competing with data packets and = gonig down to 1k PPS or 100 PPS (or 10 PPS) would result in a noticable = improvement in the flow that the acks are competing against. >=20 > Stop thinking in terms of single-flow benchmarks and near idle = 'upstream' paths. >=20 > David Lang > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat