>Number:         8217
>Category:       kern
>Synopsis:       periodic pciide pauses?
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people (Kernel Bug People)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Aug 17 14:35:00 1999
>Last-Modified:
>Originator:     Bill Sommerfeld
>Organization:
	
>Release:        19990810ish
>Environment:
	
System: NetBSD orchard.arlington.ma.us 1.4 NetBSD 1.4 (ORCHARDII) #54: Sun May 16 10:05:51 EDT 1999 sommerfeld@orchard.arlington.ma.us:/usr/src/sys/arch/i386/compile/ORCHARDII i386


>Description:
	the behavior reported in this PR has been observed on multiple
systems by multiple users (myself, Perry Metzger, Mattias Scheler)

During periods of heavy disk i/o to UDMA pciide drives, programs will
periodically "freeze" for up to about 5 seconds and then start up
again.

hopefully relevant info for the system I'm seeing it on:

desktop PIII-500 system..

pciide0 at pci0 dev 7 function 1: Intel 82371AB IDE controller (PIIX4)
pciide0: bus-master DMA support present
pciide0: primary channel wired to compatibility mode
wd0 at pciide0 channel 0 drive 0: <FUJITSU MPD3064AT>
wd0: drive supports 16-sector pio transfers, lba addressing
wd0: 6187MB, 13410 cyl, 15 head, 63 sec, 512 bytes/sect x 12672450 sectors
wd0: 32-bits data port
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2
pciide0: primary channel interrupting at irq 14
pciide0: secondary channel wired to compatibility mode
atapibus0 at pciide0 channel 1
cd0 at atapibus0 drive 0: <TOSHIBA CD-ROM XM-6502B, , 1013> type 5 cdrom removable
cd0: 32-bits data port
cd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2
pciide0: secondary channel interrupting at irq 15
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2 (using DMA data transfers)
cd0(pciide0:1:0): using PIO mode 4, Ultra-DMA mode 2 (using DMA data transfers)

oddly I cannot reproduce this on a celeron laptop which has a
controller which probes identically and which is also UDMA.

>How-To-Repeat:
	tar xzvf <large tarball> in one window
	(cd /usr/src; find . -print) in another.

	observe freezes for ~5s once or twice a minute.
>Fix:
	???
	reporting now to get it some visibility.
>Audit-Trail:
>Unformatted: