Re: [PATCH RFC 0/6] Implement per-processor data areas for i386.

[Andi Kleen <ak@suse.de>]

  
> 
> I don't think so.  The whole point is to make the pda easily accessible 
> with simple addressing modes based on %gs:.   I have been wondering if 
> we can modify the percpu mechanism to get the linker to construct the 
> layout of the pda, so that all the existing percpu stuff can be 
> transparently moved into the pda and accessed efficiently.  I think it 
> would be pretty tricky to get it all working though...

I tried that once on x86-64, but it wasn't possible because the linker
is missing the right relocations. It has something on the first look similar 
for __thread data in user space, but it wasn't usable for the kernel.

Even with a single indirection it is still far more efficient than a 
array lookup.

-Andi