kern/61669: writing to 3ware escalade (twe) spends 90% of cpu in system.

[Klaus Robert Suetterlin]

>Number:         61669
>Category:       kern
>Synopsis:       writing to 3ware escalade (twe) spends 90% of cpu in system.
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Wed Jan 21 01:50:15 PST 2004
>Closed-Date:
>Last-Modified:
>Originator:     Klaus Robert Suetterlin
>Release:        FreeBSD 5.2-CURRENT i386
>Organization:
Max-Planck-Institut
>Environment:
System: FreeBSD geclab1.cips.mpg.de 5.2-CURRENT FreeBSD 5.2-CURRENT #2: Tue Jan 20 14:35:53 CET 2004 krs at geclab1.cips.mpg.de:/usr/obj/usr/src/sys/GECLAB1 i386

I removed all INVARIANTS and WITNESS related options from the kerneli configuration.

MPTable: <COMPAQ   PROLIANT    >
CPU: Intel Pentium III (927.11-MHz 686-class CPU)
real memory  = 805306368 (768 MB)
avail memory = 782446592 (746 MB)
pcib5: <ServerWorks NB6635 3.0LE host to PCI bridge> at pcibus 5 on motherboard
pci5: <PCI bus> on pcib5
twe0: <3ware 7000 series Storage Controller. Driver version 1.50.00.000> port 0x
b040-0xb04f mem 0xd0800000-0xd0ffffff,0xd0200000-0xd020000f irq 10 at device 2.0
 on pci5
twe0: 4 ports, Firmware FE7S 1.05.00.063, BIOS BE7X 1.08.00.048

The 3ware escalade is a 8506-4LP (64Bit, 66MHz) which is plugged into a 64Bit, 33MHz pci slot.  It has 4 250GB SATA disks in Raid0.

>Description:
(I posted this to freebsd-current, but couldn't get any solution.)
Writing to the 3ware escalade uses up all my cpu time.

When I do ``dd if=/dev/zero of=/space/test bs=1000000 count=10000'', systat -vmstat reports:  500 Interrupts total, 280 in twe.  CPU usage is 90% system, 1% interrupt, 9% idle.  The twe is serving 128KB/t at 570 tps for a total of 72MB/s, beeing only 75% busy.

With INVARIANTS and WITNESS options in the kernel system uses up all cpu, but twe only serves 30MB/s.

>How-To-Repeat:
Always on.

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