Re: [patch 0/7] [RFC] SLUB: Improve allocpercpu to reduce per cpu access overhead

David Miller
2007-11-01T21:26:03Z

From: Christoph Lameter <clameter@sgi.com>
Date: Thu, 1 Nov 2007 06:01:14 -0700 (PDT)

> On Thu, 1 Nov 2007, David Miller wrote:
>
> > IA64 seems to use it universally for every __get_cpu_var()
> > access, so maybe it works out somehow :-)))
>
> IA64 does not do that. It addds the local cpu offset
>
> #define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var,
> __ia64_per_cpu_var(local_per_cpu_offset)))
> #define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var,
> __ia64_per_cpu_var(local_per_cpu_offset)))

Oh I see, it's the offset itself which is accessed at the fixed
virtual address slot.