From owner-svn-src-user@FreeBSD.ORG Fri Mar 2 10:08:24 2012 Return-Path: Delivered-To: svn-src-user@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0C861106564A; Fri, 2 Mar 2012 10:08:24 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from mail-yx0-f182.google.com (mail-yx0-f182.google.com [209.85.213.182]) by mx1.freebsd.org (Postfix) with ESMTP id 98ED18FC08; Fri, 2 Mar 2012 10:08:23 +0000 (UTC) Received: by yenl9 with SMTP id l9so533616yen.13 for ; Fri, 02 Mar 2012 02:08:23 -0800 (PST) Received-SPF: pass (google.com: domain of ivoras@gmail.com designates 10.236.155.101 as permitted sender) client-ip=10.236.155.101; Authentication-Results: mr.google.com; spf=pass (google.com: domain of ivoras@gmail.com designates 10.236.155.101 as permitted sender) smtp.mail=ivoras@gmail.com; dkim=pass header.i=ivoras@gmail.com Received: from mr.google.com ([10.236.155.101]) by 10.236.155.101 with SMTP id i65mr12702327yhk.52.1330682903217 (num_hops = 1); Fri, 02 Mar 2012 02:08:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; bh=ToLnHBqrWy4RiFxHZhCNC2WeaMoMXrQSVfH0O8EcMt4=; b=QBPWCBo72AZoZyyUHVkI9a4ow7jNO7+13qJAKVAyZcysyVW1BtDOIzINOP8/11sv0S YHMmpYT/hRHTJodjubbtNEOYbGXvAhM18NgFsFquCMcLYiudsGlUwecQv5N5EI06Ro41 bKBIo6bI4AsQ+Quf74Hx3YKr7ECVGvMOepAXC+H2Gkjlu5kcE8IL7XBl30a8YS8XFDIF Gi7C8eemCfQxg2o+teootPDy6uySkeDby0VNstmer2wqqZHOLDwJP83KVUxaLqcS6MlH kA+vjsTybwjbKJcn+pLHykHkpYlAhK6AHs+aIcrQX4NKzk8WtpL8jkWfl9/OQJ89oUcJ 4hTg== Received: by 10.236.155.101 with SMTP id i65mr9954232yhk.52.1330681591142; Fri, 02 Mar 2012 01:46:31 -0800 (PST) MIME-Version: 1.0 Sender: ivoras@gmail.com Received: by 10.101.130.23 with HTTP; Fri, 2 Mar 2012 01:45:51 -0800 (PST) In-Reply-To: <4F4FB792.5080908@freebsd.org> References: <201203011618.q21GIdww086427@svn.freebsd.org> <4F4FB792.5080908@freebsd.org> From: Ivan Voras Date: Fri, 2 Mar 2012 10:45:51 +0100 X-Google-Sender-Auth: BY17bVIoMhh2v0-E0DMh09HKMe4 Message-ID: To: Andre Oppermann Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: 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: Fri, 02 Mar 2012 10:08:24 -0000 On 1 March 2012 18:53, Andre Oppermann wrote: > I'm a bit wary of abuse by non-clueful enough people who think bigger > must be better. =C2=A0There was a recent discussion to this effect on TCP= M. > Also there were reports of congestion collapse in some networks, due > to some other issues. =C2=A0I'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. =C2=A0The (negative) effects are not directly visible to a nor= mal > admin. AFAIK the whole idea about increasing the initial window was started in Google; there are some blog posts from their engineers and at least one paper (http://code.google.com/speed/articles/tcp_initcwnd_paper.pdf). The reason why they have been able to experiment with it is that it's so easy to change in Linux: " the initial congestion window is con=EF=AC=81gured using the intitcwnd option in the ip route command. " So, by not having this as tunable, that opportunity was missed by someone who uses FreeBSD (Yahoo?). Less power to tinker results in less power to do some innovation. Even more, the quote I've pasted from the paper suggests it's a per-route setting in Linux.