bin/94415: systat(1) reports incorrect data for CD/DVD drive
Dieter
freebsd at sopwith.solgatos.com
Mon Mar 13 18:11:07 UTC 2006
>Number: 94415
>Category: bin
>Synopsis: systat(1) reports incorrect data for CD/DVD drive
>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: Mon Mar 13 18:11:05 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator: Dieter
>Release: 6.0
>Organization:
>Environment:
6.0-RELEASE amd64
>Description:
Kernel is GENERIC with addition of:
device atapicam # needed to burn dvd
AMD64 nforce4-ultra PATA CD/DVD drive
acd0: DVDR <HL-DT-ST DVDRAM GSA-4160B/A301> at ata0-master UDMA66
cd0 at ata0 bus 0 target 0 lun 0
cd0: <HL-DT-ST DVDRAM GSA-4160B A301> Removable CD-ROM SCSI-0 device
cd0: 66.000MB/s transfers
cd0: cd present [2295104 x 2048 byte records]
"systat -vmstat" reports MB/s for cd0 that is 2x the actual rate.
>How-To-Repeat:
This is with UFS/FFS on a DVD+RW, but I doubt the bug depends on that.
Run "systat -vmstat" and generate some IO on the dvd drive.
Example 1: cmp /foo/bigfile /dvd/bigfile
systat will report that cd0 has twice the MB/s of the hard drive.
Example 2: dd if=/dvd/bigfile of=/dev/null bs=1m
systat will report twice the MB/s that dd does.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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