From owner-freebsd-stable@FreeBSD.ORG Wed Jul 27 15:52:32 2005 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5A8FA16A41F for ; Wed, 27 Jul 2005 15:52:32 +0000 (GMT) (envelope-from vivek@khera.org) Received: from yertle.kcilink.com (yertle.kcilink.com [65.205.34.180]) by mx1.FreeBSD.org (Postfix) with ESMTP id 05CA743D49 for ; Wed, 27 Jul 2005 15:52:31 +0000 (GMT) (envelope-from vivek@khera.org) Received: from [192.168.7.103] (host-103.int.kcilink.com [192.168.7.103]) by yertle.kcilink.com (Postfix) with ESMTP id F0572B80C for ; Wed, 27 Jul 2005 11:52:30 -0400 (EDT) Mime-Version: 1.0 (Apple Message framework v733) In-Reply-To: <42E67972.4000700@nurfuerspam.de> References: <42E67972.4000700@nurfuerspam.de> Content-Type: multipart/signed; micalg=sha1; boundary=Apple-Mail-2-290946002; protocol="application/pkcs7-signature" Message-Id: <03E81E5E-7292-490E-8540-66B8CC4F98C4@khera.org> From: Vivek Khera Date: Wed, 27 Jul 2005 11:52:30 -0400 To: freebsd-stable@freebsd.org X-Mailer: Apple Mail (2.733) X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Re: i386 vs amd64 - benchmark results X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Jul 2005 15:52:32 -0000 --Apple-Mail-2-290946002 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed On Jul 26, 2005, at 1:57 PM, Martin wrote: > Please notice the memory speed penalties while the > system is running on amd64 kernel. I would like to > know what causes this kind of low performance when > memory is being accessed. The amd64 memory architecture is NUMA -- that is, depending on how your RAM is layed out, some of it is faster to access for each processor. Accessing RAM "local" to the other processor(s) is slower. There are many subtle issues relating to non-uniform memory access and how to code programs to take advantage of it (or try to avoid being bit by it). It is a very hard problem, and the three letters following my name came to be from researching this issue 11 years ago :-) The FreeBSD scheduler and memory allocators are definitely not NUMA aware. Vivek Khera, Ph.D. +1-301-869-4449 x806 --Apple-Mail-2-290946002--