Re: [RFC][PATCH 2/2] quicklist shouldn't be proportional to # of CPUs

[Mike Travis <travis@sgi.com>]

David Miller wrote:
> From: Andrew Morton <akpm@linux-foundation.org>
> Date: Wed, 20 Aug 2008 23:46:15 -0700
> 
>> On Wed, 20 Aug 2008 20:08:13 +0900 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
>>
>>> +	num_cpus_per_node = cpus_weight_nr(node_to_cpumask(node));

I think the more correct usage would be:

	{
		node_to_cpumask_ptr(v, node);
		num_cpus_per_node = cpus_weight_nr(*v);
		max /= num_cpus_per_node;

		return max(max, min_pages);
	}

which should load 'v' with a pointer to the node_to_cpumask_map[node] entry
[and avoid using stack space for the cpumask_t variable for those arch's
that define a node_to_cpumask_map (or similar).]  Otherwise a local cpumask_t
variable '_v' is created to which 'v' is pointing to and thus can be used
directly as an arg to the cpu_xxx ops.

Thanks,
Mike


>> sparc64 allmodconfig:
>>
>> mm/quicklist.c: In function `max_pages':
>> mm/quicklist.c:44: error: invalid lvalue in unary `&'
>>
>> we seem to have a made a spectacular mess of cpumasks lately.
> 
> It should explode similarly on x86, since it also defines node_to_cpumask()
> as an inline function.
> 
> IA64 seems to be one of the few platforms to define this as a macro
> evaluating to the node-to-cpumask array entry, so it's clear what
> platform Motohiro-san did build testing on :-)
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