From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f43.google.com (mail-pb0-f43.google.com [209.85.160.43]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 2EF3E200CCC for ; Sat, 5 May 2012 16:19:36 -0700 (PDT) Received: by pbcwz7 with SMTP id wz7so8974186pbc.16 for ; Sat, 05 May 2012 16:19:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=PhIFu+Uac5ED6pVfKkEUBpdmMqrqnCOObaOx1HCzMhY=; b=NJi9eTAXhY7eipXVE0pqAtmvcH1n001WA1JjyBTDibpE/6xjD13G0xZ9HEwTdKO/1v RCcEd9VbBlsqiHqMEnohElrybgg0hwxjOZx4N5jc1X4Vz9G4GEVkK39pBg8qlO7MaPOo iFJAIS0RzT5TP1Es7r5if9jKKyOp3ZiDH5ay5XGJzpzTQQ+OG6jJrx2x52AuD6SH6vVN wq3HQGBR2O2rYxh+G4BYqwDh5Gp4nf95BhBTwAVys1rKzxsZyJ/KKtQzKC9dmLtp1lga 5qtOvOfEZNkyz4UVMNW+vlZU8N1hT6ruCYsd26dhnIxh5v0qjYUVg6jWSemsNS4G3wPu feyg== Received: by 10.68.190.7 with SMTP id gm7mr12738970pbc.156.1336259974819; Sat, 05 May 2012 16:19:34 -0700 (PDT) Received: from ?IPv6:2001:4f8:3:203::c001? ([2001:4f8:3:203::c001]) by mx.google.com with ESMTPS id nv2sm13095337pbb.6.2012.05.05.16.19.33 (version=SSLv3 cipher=OTHER); Sat, 05 May 2012 16:19:33 -0700 (PDT) Message-ID: <4FA5B584.2050400@gmail.com> Date: Sat, 05 May 2012 16:19:32 -0700 From: dave taht User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120410 Thunderbird/11.0.1 MIME-Version: 1.0 To: Eric Dumazet References: <1336217671-20384-1-git-send-email-dave.taht@bufferbloat.net> <1336218794.3752.508.camel@edumazet-glaptop> <1336229343.3752.516.camel@edumazet-glaptop> <1336249251.3752.558.camel@edumazet-glaptop> <1336250168.3752.560.camel@edumazet-glaptop> <1336252281.3752.561.camel@edumazet-glaptop> <4FA597C0.7090206@gmail.com> <1336252832.3752.563.camel@edumazet-glaptop> <4FA5A3B8.7020808@gmail.com> <1336255783.3752.573.camel@edumazet-glaptop> <4FA5AB05.9030305@gmail.com> <1336257554.3752.578.camel@edumazet-glaptop> <4FA5AE25.1080506@gmail.com> <1336259238.3752.611.camel@edumazet-glaptop> In-Reply-To: <1336259238.3752.611.camel@edumazet-glaptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: codel@lists.bufferbloat.net, =?UTF-8?B?RGF2ZSBUw6RodA==?= Subject: Re: [Codel] [PATCH v5] pkt_sched: codel: Controlled Delay AQM 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: Sat, 05 May 2012 23:19:36 -0000 On 05/05/2012 04:07 PM, Eric Dumazet wrote: > On Sat, 2012-05-05 at 15:48 -0700, dave taht wrote: > >> Stalking butterflies. ( >> http://en.wikipedia.org/wiki/File:Lorenz_attractor_yb.svg ) >> >> I suspected also we would have issues as we hit some natural quantums >> (clock rate/interrupt rate/bql estimator etc) but for all I know it's >> just a plain bug. I need a reboot. Goin to dinner. >> > This part of Codel seems suspicious (last page ) > > // If min went above target close to when we last went below it > // assume that the drop rate that controlled the queue on the > // last cycle is a good starting point to control it now. > if (now - drop_next< 16.*interval) { > int c = count - 1; > count = c<1? 1 : c; > else { > count = 1; > } > > > I suggest to replace it by a more conservative algo : > > // If min went above target close to when we last went below it > // assume that sqrt(half) the drop rate that controlled the queue on the > // last cycle is a good starting point to control it now. > if (now - drop_next< 16.*interval) { > int c = count>> 1; > count = c<1? 1 : c; > else { > count = 1; > } > I don't buy it. See previous mail. count - some_x sure. > With this change, my q->count max value is 12000 > > >