From owner-freebsd-net@FreeBSD.ORG Sat Nov 29 20:39:50 2008 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D6C6E1065670 for ; Sat, 29 Nov 2008 20:39:50 +0000 (UTC) (envelope-from venkatvenkatsubra@yahoo.com) Received: from web58304.mail.re3.yahoo.com (web58304.mail.re3.yahoo.com [68.142.236.157]) by mx1.freebsd.org (Postfix) with SMTP id 9B6CC8FC25 for ; Sat, 29 Nov 2008 20:39:50 +0000 (UTC) (envelope-from venkatvenkatsubra@yahoo.com) Received: (qmail 94704 invoked by uid 60001); 29 Nov 2008 20:39:50 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:Cc:MIME-Version:Content-Type:Message-ID; b=oDUpg8LE1Ug6BD8friREb82glHc/QwnL4TPO6XttR4aUScKzatXzxqUhUmlt9HNoqITM4M0ZYGxnpBH4p9Jed1cGK0e+7/Ks5cc0kncCuhFCy3Q44/AzO6dJSs8GSx6SwAxhFK6UH/GmBv9CmflN8vpQhHz7DDyV+1uvBpQzPhU=; X-YMail-OSG: 4sC7_gYVM1mjIeF62ZOBBYYTXGZzpiGpGB7SK09HNYLUpYwkfOXwuh9J71Nbk1WiMWMylLPqDNM6krOu_JWUL1qacB3nvxyNRAhdIiCBPm9nXYdwWysPF0kkIZBDSI6AqNavIyqNY3cb0JwSOGmTruFZHCkgm.ZfvD1xcCvZeN1hF5n1wcV2d39kTlpD Received: from [70.112.131.248] by web58304.mail.re3.yahoo.com via HTTP; Sat, 29 Nov 2008 12:39:49 PST X-Mailer: YahooMailRC/1155.32 YahooMailWebService/0.7.260.1 References: <200811291746.aa88825@walton.maths.tcd.ie> Date: Sat, 29 Nov 2008 12:39:49 -0800 (PST) From: Venkat Venkatsubra To: David Malone MIME-Version: 1.0 Message-ID: <10716.94191.qm@web58304.mail.re3.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Rui Paulo , freebsd-net@freebsd.org, Kevin Oberman Subject: Re: FreeBSD Window updates X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 29 Nov 2008 20:39:51 -0000 Hi David,=0A=0AAssuming each of these 5 window updates are sent after the a= pps=0Acompleted the=A0read that it issued, what's the buffer size the apps = is passing=0Ato the read ? If it is small, could that be increased ?=0A=0AB= ut I agree with you that there is room for optimizing sending of these wind= ow updates.=0A=0A(Since I don't know the window scale factor for the connec= tion, I couldn't figure out=0Ahow much each of the window updates was openi= ng up the window.)=0A=0AVenkat=0A=0A=0A________________________________=0AF= rom: David Malone =0ATo: Venkat Venkatsubra =0ACc: Rui Paulo ; freebsd-net@freebs= d.org; Kevin Oberman =0ASent: Saturday, November 29, 2008 1= 1:46:30 AM=0ASubject: Re: FreeBSD Window updates=0A=0AI've got an example e= xtract tcpdump of this at the end of the mail=0A- here 6 ACKs are sent, 5 o= f which are pure window updates and=0Aseveral are 2us apart!=0A=0AI think t= he easy option is to delete the code that generates explicit=0Awindow updat= es if the window moves by 2*MSS. We then should be doing=0Asomething simila= r to Linux. The other easy alternative would be to=0Aadd a sysclt that lets= us generate an window update every N*MSS and=0Aby default set it to someth= ing big, like 10 or 100. That should=0Aeffectively eliminate the updates du= ring bulk data transfer, but=0Amay still generate some window updates after= a loss.=0A=0ANormal ACKing for driving congestion control shouldn't be imp= acted=0Aby either of these suggested changes.=0A=0A=A0=A0=A0 David.=0A=0A12= 27622713.276609 172.16.2.2.5002 > 172.16.1.51.39077: . ack 144097745 win 40= 798 (DF)=0A1227622713.276611 172.16.2.2= .5002 > 172.16.1.51.39077: . ack 144097745 win 40830 (DF)=0A1227622713.276613 172.16.2.2.5002 > 172.16.1.51.39077:= . ack 144097745 win 40862 (DF)=0A12276= 22713.276615 172.16.2.2.5002 > 172.16.1.51.39077: . ack 144097745 win 40894= (DF)=0A1227622713.276852 172.16.2.2.50= 02 > 172.16.1.51.39077: . ack 144097745 win 40926 (DF)=0A1227622713.276855 172.16.2.2.5002 > 172.16.1.51.39077: . = ack 144097745 win 40958 (DF)=0A12276227= 13.296585 172.16.2.2.5002 > 172.16.1.51.39077: . ack 144100641 win 40956 (DF)=0A__________________________________= _____________=0Afreebsd-net@freebsd.org mailing list=0Ahttp://lists.freebsd= .org/mailman/listinfo/freebsd-net=0ATo unsubscribe, send any mail to "freeb= sd-net-unsubscribe@freebsd.org"=0A=0A=0A=0A