Re: [RFC 00/15] x86_64: Optimize percpu accesses

[Jeremy Fitzhardinge]

Christoph Lameter wrote:
> > The nice thing about the non-zero-based scheme i386 uses is that setting
> > gs-base to zero means that percpu variables accesses get directly to the
> > prototype percpu data area, which simplifies boot time setup (which is
> > doubly awkward on 32-bit because you need to generate a GDT entry rather
> > than just load an MSR as you do in 64-bit).
> >     
>
> Great but it causes trouble in other ways as discussed.

What other trouble?  It works fine.

>  Its best to consistently access
> per cpu variables using the segment registers.
>   


It is, but initially the segment base is 0, so just using a percpu 
variable does something sensible from the start with no special setup.

   J
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