linux-kernel - Re: [PATCH 0/4] x86_64: Optimize percpu accesses

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Date:	Sat, 26 Jul 2008 14:38:19 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Mike Travis <travis@....com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Hugh Dickins <hugh@...itas.com>,
	Jack Steiner <steiner@....com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] x86_64: Optimize percpu accesses


* Mike Travis <travis@....com> wrote:

> This patchset provides the following:
> 
>   * x86_64: Cleanup setup_percpu by fixing some minor potential
>     problems as well as add some debugging aids.
> 
>   * x86_64: Rebase per cpu variables to zero
> 
>     Rebase per cpu variables to zero in preparation for the following
>     patch to fold the pda into the per cpu area.
> 
>   * x86_64: Fold pda into per cpu area
> 
>     Declare the pda as a per cpu variable. This will allow the per cpu
>     variables to be accessible on the x86_64 using %gs as the base of
>     the percpu areas for each cpu:
> 
> 	%gs:per_cpu_xxxx
> 
>   * x86_64: Reference zero-based percpu variables offset from gs
> 
>     Actually implement the above operation for __get_cpu_var() and
>     __put_cpu_var().  Since this is now a single instruction, we
>     can remove the non-preemptible versions of x86_read_percpu()
>     and x86_write_percpu().
> 
> Note that the following changes are NOT in this patchset as the plan now
> seems to be that the common (to x86) variables that are in the pda should
> be made individual per cpu variables, leaving only the stack canary in place.
> 
>   * x86_64: Replace cpu_pda ops with percpu ops
>   * x86_64: Replace xxx_pda() operations with x86_xxx_percpu().
>   * x86_64: Remove xxx_pda() operations
>   * x86_64: Remove cpu_pda() macro
> 
> Based on linux-2.6.tip/master.

i've added these patches to tip/x86/percpu-zerobased, but not yet merged 
into tip/master. I've made it -git based - does this patchset have any 
functional dependencies on other patches?

	Ingo
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