SMP in 5.1 cant deactivate hyperthreading

[Tom Samplonius]

On Thu, 12 Jun 2003, Killing wrote:

> ----- Original Message ----- 
> From: "Doug White" <dwhite at gumbysoft.com>
> > > sysctl machdep.hlt_logical_cpus:
> > > machdep.hlt_logical_cpus: 1
> > 
> > Halting them will still cause the CPUs to be detected. They just won't do
> > any useful work.
> 
> Yep but the issue is that all the core admin tools are unaware of this and
> hence include the virtual cores in idle calcs etc making load monitoring
> impossible without nasty cludges :(
> 
> So what's the way forward?
> 1. Dont just use halt have a compile or other directive to disable them?
> 2. Update all tools to be halt aware?
> 
> Personally I'd go with 2 all be it more work / ramifications on other 3rd party
> tools as it gives the benefit of also working when physical CPU's are halted.

  Well, hyperthreading can be disabled via a kernel directive, right?

> Which ever it needs someone to pick it up ASAP dont you think?

  Really?  What's the hurry?  FreeBSD 5.x isn't even bootable/installable
on a number of SMP machines yet (ex.  Dell Poweredge 6350).

>     Steve


Tom