Bug 94410

Summary:	Cannot disable hyperthreading if more than one physical processor exists
Product:	Base System	Reporter:	Pete French <petefrench>
Component:	kern	Assignee:	Mark Linimon <linimon>
Status:	Closed FIXED
Severity:	Affects Only Me
Priority:	Normal
Version:	6.0-RELEASE
Hardware:	Any
OS:	Any

Description Pete French 2006-03-13 15:30:16 UTC

	If an SMP kernel is run on a machine with more than one physical
	processor there seems to be no way to disable hyperthreading.
	The usual flags appear to set the masks correctly, but I am still
	seeing processes scheduled on 4 CPUs in 'top'. This machine
	only has two physical CPUs. In a machine with only one physical
	CPU then the behaviour works as expected.

How-To-Repeat: 
	Boot up 6.0 on a machine with more than one hyperthreading capabale
	processors installed, but with the flags turned off and observer
	that processes are still scheduled on all the hyperthreading processors.

Comment 1 Mark Linimon freebsd_committer

2007-05-26 06:57:29 UTC

State Changed
From-To: open->feedback

Is this still a problem with recent versions of FreeBSD?

Comment 2 Mark Linimon freebsd_committer

2007-05-26 06:57:29 UTC

Responsible Changed
From-To: freebsd-bugs->linimon

Comment 3 Mark Linimon freebsd_committer

2007-05-28 13:26:05 UTC

State Changed
From-To: feedback->closed

Submitter no longer has the hardware to reproduce this.  If someone else 
is having this problem, we'll open another PR.