kern/103532: Interrupt storm in 6.2-PRERELEASE

[Yoshihiro Ota]

>Number:         103532
>Category:       kern
>Synopsis:       Interrupt storm in 6.2-PRERELEASE
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Sep 23 21:20:25 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Yoshihiro Ota
>Release:        FreeBSD 6.2-PRERELEASE i386
>Organization:
>Environment:
System: FreeBSD xxx.yyy.com 6.2-PRERELEASE FreeBSD 6.2-PRERELEASE #23: Wed Sep 20 00:16:08 EST 2006 root at xxx.yyy.com:/usr/obj/usr/src/sys/GENERIC i386

ad0: 57231MB <TOSHIBA MK6021GAS GA024A> at ata0-master PIO4
acd0: CDRW <DW-224E-A/7.2A> at ata1-master UDMA33
da0 at umass-sim0 bus 0 target 0 lun 0
da0: <SAMSUNG SP2514N 0000> Fixed Direct Access SCSI-0 device 
da0: 40.000MB/s transfers
da0: 238475MB (488397168 512 byte sectors: 255H 63S/T 30401C)

>Description:
When heavy I/O occurs, interrupts eat almost all available CPU.
When the same operation is done on 6.1-RELEASE, the CPU use and the 
number of interrupts are very low.

It seems that it only happens with my ad0 device in my system.
I did not see many interrupts when I did the same command on da0 device.

>How-To-Repeat:

# mount /dev/ad0sX /mnt/tmp
# tar xf /path/to/ports.tar.gz -C /mnt/tmp

>Fix:

	


>Release-Note:
>Audit-Trail:
>Unformatted: