From owner-freebsd-net@FreeBSD.ORG Mon Feb 11 18:56:05 2013 Return-Path: Delivered-To: net@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id C803DE9A; Mon, 11 Feb 2013 18:56:05 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-we0-x22a.google.com (we-in-x022a.1e100.net [IPv6:2a00:1450:400c:c03::22a]) by mx1.freebsd.org (Postfix) with ESMTP id E0D1A756; Mon, 11 Feb 2013 18:56:04 +0000 (UTC) Received: by mail-we0-f170.google.com with SMTP id z53so5064932wey.15 for ; Mon, 11 Feb 2013 10:56:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=yXPpR/wMSfetdIjc8PDfcE0gg4X9OntilrQb8cikqJ4=; b=vhbPBsNDWOcVFyKI58fxUhsVv+zp20TeaYgnNQ2nshOi41rMVVif3EqZGB+KJ8qBZY X9pRMKYCidntqREKXLUS59BD6nqTBOPuuucua2yvtCOh1tu2nuKF62uv96PzbgXsKX1f wBW160PHGt1MjtEo4c+uXpwEOkGew6yr02nFw65N9eIe02RRttfmTOJEjTqO5VIrX3QT QzjPfSSeUhKsYlyYS1WRjCWvjlfHx0REOOGoxGbUQw27axJjcEu1beeozq9np5uDHttL ks7Cavq9Fz45RR1kjiEdSwVd+lnbBjj1bxOlt13k1y7cz4T/ttqnmtnpHr78650sZbwp rIMw== MIME-Version: 1.0 X-Received: by 10.194.161.135 with SMTP id xs7mr26045457wjb.41.1360608963933; Mon, 11 Feb 2013 10:56:03 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.216.236.88 with HTTP; Mon, 11 Feb 2013 10:56:03 -0800 (PST) In-Reply-To: <5118D375.5000501@freebsd.org> References: <201301221511.02496.jhb@freebsd.org> <50FF06AD.402@networx.ch> <061B4EA5-6A93-48A0-A269-C2C3A3C7E77C@lakerest.net> <201302060746.43736.jhb@freebsd.org> <511292C9.4040307@mu.org> <51166019.9040104@mu.org> <51177818.2090900@FreeBSD.org> <5118D375.5000501@freebsd.org> Date: Mon, 11 Feb 2013 10:56:03 -0800 X-Google-Sender-Auth: UUPIg4uy-GRBnSJlg5xrKj25h3g Message-ID: Subject: Re: [PATCH] Add a new TCP_IGNOREIDLE socket option From: Adrian Chadd To: Andre Oppermann Content-Type: text/plain; charset=ISO-8859-1 Cc: John Baldwin , Alfred Perlstein , Randall Stewart , Kevin Oberman , net@freebsd.org, Andrey Zonov X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Feb 2013 18:56:05 -0000 On 11 February 2013 03:18, Andre Oppermann wrote: > In general Google does provide quite a bit of data with their experiments > showing that it isn't harmful and that it helps the case. > > Smaller RTO (1s) has become a RFC so there was very broad consensus in > TCPM that is a good thing. We don't have it yet because we were not fully > compliant in one case (loss of first segment). I've fixed that a while > back and will bring 1s RTO soon to HEAD. > > I'm pretty sure that Google doesn't ignore idle on their Internet facing > servers. They may have proposed a decay mechanism in the past. I'd have > to check the TCPM archives for that. Argh, the "If google does, it it must be fine" argument. Does Google publish the data for these experiments with the international and local links broken down? Google run a highly distributed infrastructure (this isn't news for anyone, I know) and thus the link distance, RTT, number of hops, etc may not accurately reflect "the internet". It may accurately reflect "the internet from the perspective of being roughly within the same city or state" in a lot of cases. The TCP congestion algorithms aren't just for avoiding congestion over a peering fabric and last-mile ISP infrastructure. The effects of tweaking congestion algorithms for delivery over a local peering infrastructure where you try to run things as un-congested as possible (where congestion is now The ISPs Problem) where you maintain tight control over as much of the network infrastructure as you can is likely going to be very different to the congestion algorithm behaviour needed for some end-node speaking to a variety of end-nodes over a longer, more varying set of international links. You know, what TCP congestion algorithms are also trying to "play fair" with. Please - as much as I applaud Google for what they do, please don't generalise their results to "the greater internet" without looking at the many caveats/assumptions. Adrian