From owner-freebsd-performance@FreeBSD.ORG Sat Dec 23 01:00:45 2006 Return-Path: X-Original-To: freebsd-performance@FreeBSD.org Delivered-To: freebsd-performance@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 0157116A506 for ; Sat, 23 Dec 2006 01:00:45 +0000 (UTC) (envelope-from markir@paradise.net.nz) Received: from smtp4.clear.net.nz (smtp4.clear.net.nz [203.97.37.64]) by mx1.freebsd.org (Postfix) with ESMTP id BC1D513C448 for ; Sat, 23 Dec 2006 01:00:44 +0000 (UTC) (envelope-from markir@paradise.net.nz) Received: from [192.168.1.11] (121-72-69-162.dsl.telstraclear.net [121.72.69.162]) by smtp4.clear.net.nz (CLEAR Net Mail) with ESMTP id <0JAP006OEC4XLV10@smtp4.clear.net.nz> for freebsd-performance@FreeBSD.org; Sat, 23 Dec 2006 14:00:34 +1300 (NZDT) Date: Sat, 23 Dec 2006 14:00:33 +1300 From: Mark Kirkwood In-reply-to: <20061222171431.L18486@delplex.bde.org> To: Bruce Evans Message-id: <458C7FB1.9020002@paradise.net.nz> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <458B3651.8090601@paradise.net.nz> <20061222171431.L18486@delplex.bde.org> User-Agent: Thunderbird 1.5.0.8 (X11/20061129) Cc: freebsd-performance@FreeBSD.org Subject: Re: Cached file read performance X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 23 Dec 2006 01:00:45 -0000 Bruce Evans wrote: > > None was attached. > (meaning the c prog yes?) I notice that it is stripped out from the web archive... so here's a link: http://homepages.paradise.net.nz/markir/download/freebsd/readtest.c >> Machines >> ======== >> - ufs2 32k blocksize, 4K fragments > ^^^^^^^^^^^^^^^^^^ > > Try using an unpessimized block size. Block sizes larger than BKVASIZE > (default 16K) fragment the buffer cache virtual memory. Right - I should have said, I saw a comment to that effect in src/sys/sys/param.h, and so I tested with 8K, 16K too, interestingly on my system 32K seemed to be faster, even for the bigger files (of course - hard to know if it was really significant...). > However, I > couldn't see much difference between block sizes of 16, 32 and 64K for > a small (32MB) md-malloced file system with a simple test program. > All versions got nearly 1/4 of bandwidth of main memory (800MB/S +-10% > an an AthlonXP with ~PC3200 memory). Cheers Mark