From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from uplift.swm.pp.se (ipv6.swm.pp.se [IPv6:2a00:801::f]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 5F92521F2D5 for ; Thu, 25 Sep 2014 01:08:35 -0700 (PDT) Received: by uplift.swm.pp.se (Postfix, from userid 501) id BF9E8A4; Thu, 25 Sep 2014 10:08:32 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=swm.pp.se; s=mail; t=1411632512; bh=GpqL0qVU0fAl7ROkLbz4On69mnkqW3ayb/uQuDGxjyo=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=qmQQWvPERJ06zT6zeKOgeka/afX29CVv/6jJvz0Wzc0xpX5a+Shd8dGNsApJtBihW yKF84Ym5QxEH28C15/ACQ8aRfjKdL8UaZRShmdMRwDOT+WPbE6/3KJQBH6D+uHzVab N4i+Eve02bHu0Q2h0V0COmCrodpSpfLRFPHaNA0U= Received: from localhost (localhost [127.0.0.1]) by uplift.swm.pp.se (Postfix) with ESMTP id BB00CA3; Thu, 25 Sep 2014 10:08:32 +0200 (CEST) Date: Thu, 25 Sep 2014 10:08:32 +0200 (CEST) From: Mikael Abrahamsson To: David Lang In-Reply-To: Message-ID: References: User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: bloat Subject: Re: [Bloat] I feel an urge to update this 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: Thu, 25 Sep 2014 08:09:04 -0000 On Thu, 25 Sep 2014, David Lang wrote: > well, even if you have a 10GE connection, you don't know how heavily > it's going to be used. No, but I will have a hunch. I don't need to *know*, I need to have a decent probability of being right. > what happens if the wrong hint is given? (either accidently or maliciously) Then you get IW10 instead of IW4. Right now if I am correct, Google does IW10 all across the board. > The approach of starting slow and ramping up works well, except in the > case where you have lots of very short connections. So I don't see a > benefit of trying to hint slowness. There may be some value in hinting > for faster ramp-ups, but what will that do to fairness with existing > systems? In my world, core network congestion isn't something that is permanent and continous, but an anomaly. So since the only port that should be congesting is my access port, I don't care about fairness. Also, we're not talking about starting off with a 1M TCP window to blast a huge chunk of data down the wire, we're talking about perhaps being a bit more agressive in increasing the window from a slightly higher initial level, let's say IW10 and instead of doubling, tripling window size, if the client hints they have a fast connection, and if the client says they have a slow connection, IW4 and increase 1.5x instead? Use same mechanisms as today, but tweak them to be a bit more or less agressive depending on what the client has hinted. I mean, why do we send MSS in TCP? Couldn't we just have a generic probing mechanism to test what MTU works? Well, that would be inefficient, so MSS helps. Same here. > But we have a number of companies who want to have things downloaded and > used as quickly as possible, so if this sort of thing really does help, > then I would expect that they would be experimenting with tweaking the > TCP stack to ramp up faster (although, you would also be expecting > outcrys about "how dare $bigcompany ignore the TCP defaults and be more > agressive, that doesn't compete fairly with $normaltraffic) Errr, google and IW10? So, already done!? -- Mikael Abrahamsson email: swmike@swm.pp.se