From owner-freebsd-stable@FreeBSD.ORG Thu Dec 21 11:52:52 2006 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id E237C16A4A0 for ; Thu, 21 Dec 2006 11:52:52 +0000 (UTC) (envelope-from markir@paradise.net.nz) Received: from smtp5.clear.net.nz (smtp5.clear.net.nz [203.97.33.68]) by mx1.freebsd.org (Postfix) with ESMTP id A6DD613C45A for ; Thu, 21 Dec 2006 11:52:52 +0000 (UTC) (envelope-from markir@paradise.net.nz) Received: from [192.168.1.11] (121-72-65-158.dsl.telstraclear.net [121.72.65.158]) by smtp5.clear.net.nz (CLEAR Net Mail) with ESMTP id <0JAM005B2CU2JY00@smtp5.clear.net.nz> for freebsd-stable@freebsd.org; Thu, 21 Dec 2006 23:22:51 +1300 (NZDT) Date: Thu, 21 Dec 2006 23:22:38 +1300 From: Mark Kirkwood In-reply-to: <200612201536.25497.pieter@degoeje.nl> To: Pieter de Goeje Message-id: <458A606E.6080008@paradise.net.nz> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <45888C68.10305@paradise.net.nz> <200612200816.51043.joao@matik.com.br> <4589128F.9030404@paradise.net.nz> <200612201536.25497.pieter@degoeje.nl> User-Agent: Thunderbird 1.5.0.8 (X11/20061129) Cc: freebsd-stable@freebsd.org Subject: Re: Cached file read performance with 6.2-PRERELEASE 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: Thu, 21 Dec 2006 11:52:53 -0000 Pieter de Goeje wrote: > On Wednesday 20 December 2006 11:38, Mark Kirkwood wrote: >> In fact if you note that the PIII HW *can* actually do 700MB/s, it >> suggests that your HW is capable of considerably more than 900MB/s - >> given that opteron's have excellent cpu to memory bandwidth, and the >> speed of your memory! > Indeed! > Copying /dev/zero to /dev/null yields more than 5GB/sec on a simple 2Ghz > Athlon64. It imagine there are quite a few extra things done when copying a > file from cache, because I can only manage to get one fifth (~1GB/sec) of the > theoretical speed. (this is with a file that fills more than half of all > memory) > Fascinating, never thought of trying that! On my 2 (essentially) identical PIII systems, doing copy /dev/zero to /dev/null yields 4.1 GB/s (Gentoo) and 2.0GB/s (FreeBSD) - so yeah, clearly both do something special in that case... (growl... we - i.e FreeBSD - seem to be slower again...tho at that sort of rate, who cares!) Cheers Mark