Date: Fri, 22 Jun 2001 08:38:12 -0700 (PDT) From: Matthew Williams <matthew@informatics.bangor.ac.uk> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/28339: Slow Disk performance on 4.3 (about half that on 4.2) Message-ID: <200106221538.f5MFcCW86479@freefall.freebsd.org>
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>Number: 28339 >Category: misc >Synopsis: Slow Disk performance on 4.3 (about half that on 4.2) >Confidential: no >Severity: serious >Priority: high >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Fri Jun 22 08:40:01 PDT 2001 >Closed-Date: >Last-Modified: >Originator: Matthew Williams >Release: 4.3 >Organization: University of Wales, Bangor. UK. >Environment: FreeBSD HOSTNAME.sees.bangor.ac.uk 4.3-REALEASE FreeBSD 4.3-RELEASE #2: Thu Jun 21 14:45:51 BST root@HOSTNAME.sees.bangor.ac.uk:/usr/src/sys/compile/P500 i386 >Description: We use dd to install Windows onto a partition. Under 4.3 the performance has reduced dramatically. I have experimented with a binary only install in 4.2 and 4.3 creating a file from /dev/zero and dd-ing it on to a unmounted raw partition. Under 4.2 I get an average throughput of about 6MB/sec but under 4.3 this drops to 3.5MB/sec. Hardware from dmesg: pcib0: <Intel 82443BX (440 BX) host to PCI bridge> on motherboard ... ata: at 0x1f0 irq 14 on atapci0 ... ... ad0: 8223MB <ST38410A> [16708/16/63] at ata0-master UDMA33 acd0: CDROM <CREATIVE CD5233E> at ata1-master using PIO4 >How-To-Repeat: Create a bin only istallation leaving a spare partition (rad0s1f - in my case) say 100M. Create a file from /dev/zero (dd count=102400 if=/dev/zero of=/usr/tmp/zero.fil). Now get iostat running on another console and do the following: dd bs=256b if=./zeros.fil of=/dev/rad0s1f A number of runs should get you a good average, the output from dd and iostat should be the same. >Fix: >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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