From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265339AbUGGTbm (ORCPT ); Wed, 7 Jul 2004 15:31:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265351AbUGGTbm (ORCPT ); Wed, 7 Jul 2004 15:31:42 -0400 Received: from mail.shareable.org ([81.29.64.88]:52912 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S265339AbUGGTbj (ORCPT ); Wed, 7 Jul 2004 15:31:39 -0400 Date: Wed, 7 Jul 2004 20:31:25 +0100 From: Jamie Lokier To: Stephen Hemminger Cc: "David S. Miller" , bert hubert , netdev@oss.sgi.com, linux-net@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] fix tcp_default_win_scale. Message-ID: <20040707193125.GA17266@mail.shareable.org> References: <20040701133738.301b9e46@dell_ss3.pdx.osdl.net> <20040701140406.62dfbc2a.davem@redhat.com> <20040702013225.GA24707@conectiva.com.br> <20040706093503.GA8147@outpost.ds9a.nl> <20040706114741.1bf98bbe@dell_ss3.pdx.osdl.net> <20040706194034.GA11021@mail.shareable.org> <20040706131235.10b5afa8.davem@redhat.com> <20040706224453.GA6694@outpost.ds9a.nl> <20040706154907.422a6b73.davem@redhat.com> <20040707110653.7c49bef1@dell_ss3.pdx.osdl.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040707110653.7c49bef1@dell_ss3.pdx.osdl.net> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Stephen Hemminger wrote: > But: isn't it better to have just one sysctl parameter set > (tcp_rmem) and set the window scale as needed rather than increasing > the already bewildering array of dials and knobs? I can't see why > it would be advantageous to set a window scale of 7 if the largest > possible window ever offered is limited to a smaller value? That's a fair question. It seems to me the only effects of a larger scale than necessary are (a) the buffer size can be increased after the connection is established, and (b) coarser granularity which can only degrade performance over low mss links. So why do we set a larger window scale than necessary? Is it to support (a)? -- Jamie