From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f171.google.com (mail-we0-f171.google.com [74.125.82.171]) (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 8AE1D2001A2 for ; Fri, 9 Mar 2012 14:08:57 -0800 (PST) Received: by werm1 with SMTP id m1so2507229wer.16 for ; Fri, 09 Mar 2012 14:08:55 -0800 (PST) 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 :content-type:content-transfer-encoding; bh=kczaYed4hnZUrIguJOKgl5iMt67Hwz7wu3NAr6vHfRo=; b=CxklZrktKixfFNqBQdvKx/iCUDbACdBWYYYW1+VT6h6uWigP9Bb1f+L177AHWce1mn 1l1cJlo62hSSc5fPEwPHCLqrPlk0zMHFTnPCPO80UAZG5kYZJIFHxH2WQ9CfRRswPDKx N+0miGznkY3yxLDsYVujtrG0S41SoE84Bl7Q4bh+MTDKsbGrwtAvuj3zyKJH4cVQ0x6V goV+beDyxFLcyAAf7w26IC9yX5nLtehn5c6T3NnyPakiy6P4HzKCuW5rdSa15CC/lkKk NmhJUK3SowRlqKMwE3JtNPl7uAUSTS3c4TT146akucsjFBWVdBZ/4fzrWKAIsiMFks2N jIxQ== MIME-Version: 1.0 Received: by 10.180.80.104 with SMTP id q8mr8456968wix.14.1331330935140; Fri, 09 Mar 2012 14:08:55 -0800 (PST) Received: by 10.223.151.8 with HTTP; Fri, 9 Mar 2012 14:08:55 -0800 (PST) In-Reply-To: <20120309215037.GI2539@paperino> References: <20120309215037.GI2539@paperino> Date: Fri, 9 Mar 2012 14:08:55 -0800 Message-ID: From: Dave Taht To: Davide Gerhard , bloat Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: Re: [Bloat] troubles with congestion (tbf vs htb) X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Mar 2012 22:08:58 -0000 Dear Davide: sounds like a job for the bloat list. I note your attachment got filtered out on your posting to netdev. None of what you describe surprises me, but I would love to duplicate your tests, exactly, against the new 3.3 kernel, which has BQL and various active AQMs, and I also remember various things around ssthresh being fiddled with over the past year. On Fri, Mar 9, 2012 at 1:50 PM, Davide Gerhard wrote: > Hi, > I am a master's student from the university of Trento, I have been doing = a > project, for the course of advanced networking (In a group of 2), focused > on the TCP congestion control. I used tc with htb to simulate a link with > 10mbit/s using a 100mbit/s real ethernet lan. Here is the code I used: > > tc qdisc add dev $INTF root handle 1: netem $DELAY $LOSS $DUPLICATE > =A0$CORRUPT $REORDENING > tc qdisc add dev $INTF parent 1:1 handle 10: htb default 1 r2q 10 > tc class add dev $INTF parent 10: classid 0:1 htb rate ${BANDW}kbit ceil > =A0${BANDW}kbit > > and here is the topology > > client -->| =A0 =A0|--> server with iperf -s > =A0 =A0 =A0 =A0 =A0| =A0 =A0| > =A0 =A0 =A0 =A0 =A0| =A0 =A0| > =A0 =A0 =A0 =A0 =A0+ =A0 =A0+ > =A0 =A0 =A0 =A0 =A0 eth0 > =A0 =A0CONGESTION machine > > The congestion machine have the following configurations: > - kernel 3.0 > - echo 1 > /proc/sys/net/ipv4/ip_forward > - echo 0 > /proc/sys/net/ipv4/conf/default/send_redirects > - echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects > - echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc > - echo 0 > /proc/sys/net/ipv4/conf/eth0/send_redirects > > The client captures the window size and ssthresh with tcp_flow_spy but we= do > not see any changes in the ssthresh and the window size is too large > compared to the bandwidth*latency product (see attachment). In a normal s= cenario, > this would be acceptable (I guess), but in order to obtain some relevant > results for our work, we need to avoid this "buffer" and to activate > the ssthresh. I have already tried to change backlog but this does > not change anything. I have also tried to use tbf with the following comm= and: > > tc qdisc add dev $INTF parent 1:1 handle 10: ftb rate ${BANDW}kbit burst = 10kb > =A0latency 1.2ms minburst 1540 > > In this case, the congestion works correctly as we expect, but if we use > netem I have to recalculate again all the needed values (correct?). Are t= here > any other solutions? > > Best regards. > /davide > > P.S Here follows the sysctl parameters used in the client: > net.ipv4.tcp_no_metrics_save=3D1 > net.ipv4.tcp_sack=3D1 > net.ipv4.tcp_dsack=3D1 > > -- > "The abdomen, the chest, and the brain will forever be shut from the intr= usion > of the wise and humane surgeon." - Sir John Eric Ericksen, British surgeo= n, > appointed Surgeon-Extraordinary to Queen Victoria 1873 > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html --=20 Dave T=E4ht SKYPE: davetaht US Tel: 1-239-829-5608 http://www.bufferbloat.net