linux-kernel - Re: [PATCH 13/16] x86: Unify cpu/apicid <-> NUMA node mapping between 32 and 64bit

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Date:	Thu, 9 Dec 2010 22:43:10 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Tejun Heo <tj@...nel.org>
cc:	linux-kernel@...r.kernel.org, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, eric.dumazet@...il.com, yinghai@...nel.org,
	brgerst@...il.com, gorcunov@...il.com, penberg@...nel.org
Subject: Re: [PATCH 13/16] x86: Unify cpu/apicid <-> NUMA node mapping between
 32 and 64bit

On Sat, 27 Nov 2010, Tejun Heo wrote:

> The mapping between cpu/apicid and node is done via apicid_to_node[]
> on 64bit and apicid_2_node[] + apic->numa_cpu_node() on 32bit.  This
> difference makes it difficult to further unify 32 and 64bit NUMA
> hanlding.
> 
> This patch unifies it by replacing both apicid_to_node[] and
> apicid_2_node[] with __apicid_to_node[] array, which is accessed by
> two accessors - set_apicid_to_node() and numa_cpu_node().  On 64bit,
> numa_cpu_node() always consults __apicid_to_node[] directly while
> 32bit goes through apic->numa_cpu_node() method to allow apic
> implementation to override it.
> 
> There are several places where using numa_cpu_node() is awkward and
> the override doesn't matter.  In those places, __apicid_to_node[] are
> used directly.

Why is it awkward? Anything outside the accessor functions or
specialized setup code using it is awkward, inconsistent and sloppy.

Thanks,

	tglx
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