[Linux-aus] HT Xeon and Linux Kernel (was Re:)

Mathew Robertson mathew at optusnet.com.au
Sat Jan 31 06:10:38 UTC 2004

> >>   Checked the specs of the machine, It has 2 processors actually. :-)
> >> There is something wrong.
> >
> > No there isn't. because it's HT, that means that each physical CPU has
> > two 'virtual' CPUs (siblings). hence your two processor machine is
> > detected as four cpus.
> Yeah but the 4 CPUs were only detected when I increased the number of
> CPUs in the kernel to 8. When it was 4, it wasn't detecting 4 virtual
> CPUs.
> Why the number should be increased to 8 to get it working right?

Because a kernel developer mistakenly assumed CPU numbering was linear.  This 
was probably a simple oversight -> maybe you could post a bug report to 


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