Re: Xeon processors &&Hyper-Threading

[James Cleverdon <jamesclv@us.ibm.com>]

On Saturday 14 June 2003 06:50 am, Mark Watts wrote:
> > You recompile the kernel for SMP as well as P4. If the motherboard
> > hasn't disabled HT capabilities, you will take full advantage of
> > the processor under Linux. Whatever "full advantage" means, is
> > not absolute, but whatever it is, will be used to its fullest.
> > Basically, if the code is I/O bound, you'll not see any difference.
> > If the code is compute-intensive, you will.
>
> I discovered that you need the 'CPU Enumeration' part of ACPI to be enabled
> otherwise the kernel only sees physical processors, not sibling HT
> processors - shouldnt this be selected automatically when you select SMP ?
> -

Not if you have enabled full ACPI, or if you don't have any P4s.  Some folks 
don't want any ACPI in their kernel at all.   8^)

It's possible for 'CPU Enumeration Only' to be turned on auto-magically, but 
no one has written comprehensive enough logic into the config code, yet....

-- 
James Cleverdon
IBM xSeries Linux Solutions
{jamesclv(Unix, preferred), cleverdj(Notes)} at us dot ibm dot com