Date: Fri, 17 Feb 2006 15:44:40 GMT From: Barry Tigner <tigner@msu.edu> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/93485: iostat reports cd0 speeds 2X actual speed Message-ID: <200602171544.k1HFiekS058545@www.freebsd.org> Resent-Message-ID: <200602171550.k1HFoCiJ031406@freefall.freebsd.org>
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>Number: 93485
>Category: misc
>Synopsis: iostat reports cd0 speeds 2X actual speed
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Feb 17 15:50:12 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator: Barry Tigner
>Release: 6.0 release i386
>Organization:
Michigan State University
>Environment:
FreeBSD ESHOP1.PA.MSU.EDU 6.0-RELEASE FreeBSD 6.0-RELEASE #2: Thu Dec 8 08:38:04 EST 2005 root@ESHOP1.PA.MSU.EDU:/usr/src/sys/i386/compile/ESHOP1 i386
>Description:
I have a new IDE DVD burner ,Toshiba TSDR5372 16X DL capable.
I wanted to investigate the read speeds of file transfers from
DVDs. To do this I made a 4.7G DVD with 4 1GB (2^30 bytes)files
on it named test1.bin test2.bin test3.bin test4.bin.
The system I am using details are:
Hardware:
Gigabyte GA-K8N-SLI
Athlon64/3500
512MB PC3200 ram
Toshiba TSDR5372 DVD writer
Seagate SATA 160G HD.
OS:
FreeBSD ESHOP1.PA.MSU.EDU 6.0-RELEASE FreeBSD 6.0-RELEASE #2: Thu Dec 8 08:38:04 EST 2005 root@ESHOP1.PA.MSU.EDU:/usr/src/sys/i386/compile/ESHOP1 i386
KDE 3.5
I mounted the DVD I created using the Toshiba DVD drive as /cdrom.
KDE reports the file transfer speeds correctly when I use the KDE
desktop to copy the 1GB files from the DVD to the HD.
If I run "iostat -w 1" as root while the transfer is occuring , the
transfer rate to AD4 shows correctly , however the transfer rate from
CD0 shows double the rate it should. Here is an example...
ESHOP1# iostat -w1
tty ad4 cd0 pass0 cpu
tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
12 66 19.96 3 0.05 63.84 0 0.00 0.00 0 0.00 2 11 64 1 22
224 231 112.00 35 3.83 64.00 118 7.37 0.00 0 0.00 2 0 5 0 94
168 78 126.74 89 11.00 64.00 354 22.10 0.00 0 0.00 5 0 13 2 80
40 78 128.00 127 15.86 64.00 507 31.72 0.00 0 0.00 7 0 14 2 78
56 78 124.58 131 15.92 64.00 507 31.72 0.00 0 0.00 8 0 14 5 74
8 78 125.44 131 16.03 64.00 509 31.84 0.00 0 0.00 5 0 13 4 77
312 78 127.12 128 15.87 64.00 509 31.84 0.00 0 0.00 9 0 14 1 77
16 78 128.00 128 15.98 64.00 511 31.97 0.00 0 0.00 10 0 14 2 74
0 78 124.61 132 16.05 64.00 513 32.09 0.00 0 0.00 8 0 14 0 79
0 78 128.00 129 16.11 64.00 511 31.97 0.00 0 0.00 9 0 14 2 76
24 78 126.26 129 15.89 64.00 507 31.72 0.00 0 0.00 8 0 17 1 75
0 78 127.12 128 15.87 64.00 507 31.72 0.00 0 0.00 7 0 16 2 76
0 78 126.26 129 15.89 64.00 507 31.72 0.00 0 0.00 5 0 16 1 78
40 78 127.12 128 15.87 64.00 509 31.84 0.00 0 0.00 8 0 13 3 76
It can be clearly seen that the CD0 speeds are reported as 2X the AD4 speeds,
even though they should be identical since I am just copying from one media
to another.
>How-To-Repeat:
use iostat to monitor transfer rates on the cd0 device.
>Fix:
be aware of the problem, so you don't get excited about 32MB/S transfer rates
from a DVD drive when they are actually 16MB/S.
>Release-Note:
>Audit-Trail:
>Unformatted:
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