From owner-svn-src-user@FreeBSD.ORG Thu Mar 1 18:20:16 2012 Return-Path: Delivered-To: svn-src-user@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id DA93D106564A for ; Thu, 1 Mar 2012 18:20:16 +0000 (UTC) (envelope-from andre@freebsd.org) Received: from c00l3r.networx.ch (c00l3r.networx.ch [62.48.2.2]) by mx1.freebsd.org (Postfix) with ESMTP id 46DA28FC15 for ; Thu, 1 Mar 2012 18:20:15 +0000 (UTC) Received: (qmail 33654 invoked from network); 1 Mar 2012 16:08:21 -0000 Received: from c00l3r.networx.ch (HELO [127.0.0.1]) ([62.48.2.2]) (envelope-sender ) by c00l3r.networx.ch (qmail-ldap-1.03) with SMTP for ; 1 Mar 2012 16:08:21 -0000 Message-ID: <4F4FB792.5080908@freebsd.org> Date: Thu, 01 Mar 2012 18:53:22 +0100 From: Andre Oppermann User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:9.0) Gecko/20111222 Thunderbird/9.0.1 MIME-Version: 1.0 To: Maxim Konovalov References: <201203011618.q21GIdww086427@svn.freebsd.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Michael Tuexen , src-committers@FreeBSD.ORG, svn-src-user@FreeBSD.ORG Subject: Re: svn commit: r232345 - user/andre/tcp_workqueue/sys/netinet X-BeenThere: svn-src-user@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the experimental " user" src tree" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 01 Mar 2012 18:20:16 -0000 On 01.03.2012 18:05, Maxim Konovalov wrote: >>>> Author: andre >>>> Date: Thu Mar 1 16:18:39 2012 >>>> New Revision: 232345 >>>> URL: http://svn.freebsd.org/changeset/base/232345 >>>> >>>> Log: >>>> Increase the initial CWND to 10 segments as defined in IETF TCPM >>>> draft-ietf-tcpm-initcwnd-03 discussing why the higher initial window >>>> improves the overall performance of many web services without risking >>>> congestion collapse. >>>> >>>> As long as it remains a draft it is not enabled by default and placed >>>> under a sysctl marking it clearly as experimental: >>>> net.inet.tcp.exprimental.initcwnd10 >>>> >>>> Linux as of kernel 3.0 has enabled it by default. >>>> >>> Wouldn't it be better to just let user to specify icwnd size? >> In SCTP we have a sysctl which gives the IW in MSS... >> > Yes, that's why I'm asking mainly. I'm a bit wary of abuse by non-clueful enough people who think bigger must be better. There was a recent discussion to this effect on TCPM. Also there were reports of congestion collapse in some networks, due to some other issues. I've even seen botched windows servers that respond with an icwnd of 64K. Hence I'd rather not have it open to anyone to fumble with this important parameter. The (negative) effects are not directly visible to a normal admin. -- Andre