kern/83406: SMP: em/bge drivers: severe performance loss

[Christian Wittenhorst]

>Number:         83406
>Category:       kern
>Synopsis:       SMP: em/bge drivers: severe performance loss
>Confidential:   no
>Severity:       critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Jul 13 20:00:36 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Christian Wittenhorst
>Release:        5.4-RELEASE-p4
>Organization:
progon network engineering
>Environment:
FreeBSD silver.kanti-zug.ch.internal 5.4-RELEASE-p4 FreeBSD 5.4-RELEASE-p4 #1: Wed Jul 13 19:15:08 UTC 2005     root at silver.kanti-zug.ch.internal:/usr/src/sys/i386/compile/silver  i386
>Description:
On a dual Intel Xeon server (ASUS NCL-DS motherboard) the network performance drops dramatically when SMP is enabled. Figures are: FTP 20MBps->3MBps, Samba 25MBps->2MBps, NFS 27MBps->1.7MBps. This affects at least em and bge drivers. No errors in any log. Disk performance is not affected!
>How-To-Repeat:

>Fix:
sysctl machdep.cpu_idle_hlt=0 
   restores the original performance 
>Release-Note:
>Audit-Trail:
>Unformatted: