From owner-freebsd-arch@FreeBSD.ORG Sun Mar 20 19:15:22 2011 Return-Path: Delivered-To: arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 915D2106564A for ; Sun, 20 Mar 2011 19:15:22 +0000 (UTC) (envelope-from gordon@tetlows.org) Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com [209.85.214.54]) by mx1.freebsd.org (Postfix) with ESMTP id 2D6FD8FC0C for ; Sun, 20 Mar 2011 19:15:21 +0000 (UTC) Received: by bwz12 with SMTP id 12so5153262bwz.13 for ; Sun, 20 Mar 2011 12:15:20 -0700 (PDT) MIME-Version: 1.0 Received: by 10.204.189.1 with SMTP id dc1mr2889923bkb.34.1300648520328; Sun, 20 Mar 2011 12:15:20 -0700 (PDT) Received: by 10.204.16.65 with HTTP; Sun, 20 Mar 2011 12:15:20 -0700 (PDT) In-Reply-To: References: <132388F1-44D9-45C9-AE05-1799A7A2DCD9@neville-neil.com> Date: Sun, 20 Mar 2011 12:15:20 -0700 Message-ID: From: Gordon Tetlow To: Navdeep Parhar Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: arch@freebsd.org, George Neville-Neil Subject: Re: Updating our TCP and socket sysctl values... X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 20 Mar 2011 19:15:22 -0000 On Sat, Mar 19, 2011 at 6:19 PM, Navdeep Parhar wrote: > I meant 100us (microseconds), sorry. =A0My point still stands - 10G > networks have much less one way delay than this. =A0The worst =A0I can > find in the lab right now has around ~30us delay. =A0A socket rcv > bufsize of 64K maxes out the link in some casual testing with netperf > (with autosizing disabled). =A0256K is already more than what's needed. Let's look at something much more realistic on the internet. How about a 100Mbps link with 100ms delay. That's downloading something from Europe from the US. I do this at work all of the time. The BDP for such a link is ~1.2MB. This is a pretty common scenario today and it's not even close to what is reasonably capable (a reliable 1Gbps link over the same delay distance). Looking at other operating systems: Linux (CentOS 5.4): Read window: Initial: 87380 Max: 4194304 Write window: Initial: 16384 Max: 4194304 Solaris 10: Read window: Initial: 49152 Max: 1048576 Write window: Initial: 49152 Max: 1048576 What is the FreeBSD initial setting? Is that sendspace (32k) and recvspace (64k)? Should we look at changing those too or just discuss the maximum window sizes? Gordon