kern/109936: SMP kernel performance problem on FSC TX600

[Ludger Bolmerg]

>Number:         109936
>Category:       kern
>Synopsis:       SMP kernel performance problem on FSC TX600
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Mar 05 18:20:03 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Ludger Bolmerg
>Release:        6.2
>Organization:
>Environment:
FreeBSD bsd60.myname.de 6.2-RELEASE-p2 FreeBSD 6.2-RELEASE-p2 #1
>Description:
I installed FreeBSD 6.2 on a Fujitsu Siemens TX600 S3 with 2 dual core Xeon processors and 4G RAM.
Here is the link to the data sheet of the server on Fujitsu-Siemens' Web page.  It may be helpful

http://extranet.fujitsu-siemens.com/vil/pc/vil/primergy/model_line_400/rack_server/ds_prim-rx600-s3.pdf

The SMP kernel is awfully slow.  make buildkernel takes about 6 hours to complete.  When I boot a UP kernel the build completes within 12 minutes.  I don't see any unusual message in any log file.

Booting the SMP kernel with kern.smp.disabled=1 shows good performance values.

When booting the SMP kernel with 

hint.lapic.10.disabled=1
hint.lapic.12.disabled=1
hint.lapic.14.disabled=1

also results in good performance.  Disabling single CPUs didn't work. I had to apply a patch provided by John Baldwin.
http://lists.freebsd.org/pipermail/freebsd-smp/2007-February/001320.html

Disabling all but one CPU also gives good performance. As soon as the second CPU gets enabled it becomes slow again.



>How-To-Repeat:
Install on same hardware
>Fix:

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