From owner-freebsd-arch@FreeBSD.ORG Sun Mar 20 01:00:20 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 9960E10656D9 for ; Sun, 20 Mar 2011 01:00:20 +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 36D928FC0A for ; Sun, 20 Mar 2011 01:00:19 +0000 (UTC) Received: by bwz12 with SMTP id 12so4774341bwz.13 for ; Sat, 19 Mar 2011 18:00:19 -0700 (PDT) MIME-Version: 1.0 Received: by 10.204.81.27 with SMTP id v27mr2264393bkk.115.1300581516533; Sat, 19 Mar 2011 17:38:36 -0700 (PDT) Received: by 10.204.16.65 with HTTP; Sat, 19 Mar 2011 17:38:36 -0700 (PDT) In-Reply-To: References: <132388F1-44D9-45C9-AE05-1799A7A2DCD9@neville-neil.com> Date: Sat, 19 Mar 2011 17:38:36 -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 01:00:20 -0000 On Sat, Mar 19, 2011 at 4:13 PM, Navdeep Parhar wrote: > 256KB seems adequate for 10G (as long as the consumer can keep > draining the socket rcv buffer fast enough). =A0If you consider 2 x > bandwidth delay product to be a reasonable socket buffer size then > 256K allows for 10G networks with ~100ms delays. =A0Normally the delay > is _way_ less than this for 10G and even 256K may be an overkill (but > this is ok, the kernel has tcp_do_autorcvbuf on by default) The BDP for a 10Gbps link with 100ms delay is about 120MB. Here's a decent calculator for figuring it out: http://www.speedguide.net/bdp.php Regards, Gordon