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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: Slow Disk performance on 4.3 (about half that on 4.2)
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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:    roam
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jun 22 08:40:01 PDT 2001
>Closed-Date:    Tue Apr 09 00:32:30 PDT 2002
>Last-Modified:  Tue Apr 09 00:32:30 PDT 2002
>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:

From: Peter Pentchev <roam@orbitel.bg>
To: Matthew Williams <matthew@informatics.bangor.ac.uk>
Cc: freebsd-gnats-submit@FreeBSD.org
Subject: Re: misc/28339: Slow Disk performance on 4.3 (about half that on 4.2)
Date: Fri, 22 Jun 2001 19:08:50 +0300

 On Fri, Jun 22, 2001 at 08:38:12AM -0700, Matthew Williams wrote:
 > 
 > >Number:         28339
 > >Category:       misc
 > >Synopsis:       Slow Disk performance on 4.3 (about half that on 4.2)
 > >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.
 
 4.3 has IDE write caching off by default.  To enable it, add this line:
 
 hw.ata.wc="1"
 
 to the /boot/loader.conf file, and reboot.
 
 G'luck,
 Peter
 
 -- 
 "yields falsehood, when appended to its quotation." yields falsehood, when appended to its quotation.
State-Changed-From-To: open->feedback 
State-Changed-By: roam 
State-Changed-When: Sat Jun 23 04:02:39 PDT 2001 
State-Changed-Why:  
Does setting the hw.ata.wc tunable, as suggested in my previous mail, 
work for you? 


Responsible-Changed-From-To: freebsd-bugs->roam 
Responsible-Changed-By: roam 
Responsible-Changed-When: Sat Jun 23 04:02:39 PDT 2001 
Responsible-Changed-Why:  
I'll keep track of the reply. 

http://www.FreeBSD.org/cgi/query-pr.cgi?pr=28339 
State-Changed-From-To: feedback->closed 
State-Changed-By: roam 
State-Changed-When: Tue Apr 9 00:31:39 PDT 2002 
State-Changed-Why:  
Feedback timeout (> 10 months) 

http://www.freebsd.org/cgi/query-pr.cgi?pr=28339 
>Unformatted:
