From owner-freebsd-performance@FreeBSD.ORG Thu Nov 18 23:12:14 2004 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 31A0516A4CE for ; Thu, 18 Nov 2004 23:12:14 +0000 (GMT) Received: from note.orchestra.cse.unsw.EDU.AU (note.orchestra.cse.unsw.EDU.AU [129.94.242.24]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5BEC343D53 for ; Thu, 18 Nov 2004 23:12:13 +0000 (GMT) (envelope-from lukem@cse.unsw.edu.au) Received: From wagner With LocalMail ; Fri, 19 Nov 2004 10:11:59 +1100 From: lukem.freebsd@cse.unsw.edu.au Sender: lukem@cse.unsw.edu.au To: Aaron Glenn Date: Fri, 19 Nov 2004 10:11:59 +1100 (EST) In-Reply-To: <18f6019404111809224fb97c06@mail.gmail.com> Message-ID: References: <20041118101026.55888.qmail@web14121.mail.yahoo.com> <20041118105543.10295.qmail@web41208.mail.yahoo.com> <18f6019404111809224fb97c06@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed cc: freebsd-performance@freebsd.org cc: =?ISO-8859-1?Q?Arne_W=F6rner?= Subject: Re: I've ran out of ideas X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Nov 2004 23:12:14 -0000 On Thu, 18 Nov 2004, Aaron Glenn wrote: > d# dd if=/dev/ad2s1 of=/dev/null bs=64k count=1000 > 1000+0 records in > 1000+0 records out > 65536000 bytes transferred in 1.353203 secs (48430278 bytes/sec) > d# > > iostat has never gone above 3.8MB/s The simple answer is that both iostat and dd are giving you the correct results. Try your dd again with a smaller block size (like the 512 byte default) and you should see that disk throughput is closer to what you are seeing for your web server. I would theorise that your web server is probably only issuing fairly small disk reads, so your network performance is being bound by the disk. To test this theory, you could: * create an mfs partition and serve off it to see what kind of performance you can get * see if you can tweak the web server to use larger reads and writes. In your original message you said that increasing the disk block size improved performance, which would also indicate that you are being limited by disk performance. -- Luke