bin/94415: systat(1) reports incorrect data for CD/DVD drive

[Dieter]

>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: