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

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 21 Aug 2008 00:13:22 -0700 (PDT) David Miller <davem@davemloft.net> 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));
> > 
> > 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 :-)

Seems to compile OK on x86_32, x86_64, ia64 and powerpc for some reason.

This seems to fix things on sparc64:

--- a/mm/quicklist.c~mm-quicklist-shouldnt-be-proportional-to-number-of-cpus-fix
+++ a/mm/quicklist.c
@@ -28,7 +28,7 @@ static unsigned long max_pages(unsigned 
 	unsigned long node_free_pages, max;
 	int node = numa_node_id();
 	struct zone *zones = NODE_DATA(node)->node_zones;
-	int num_cpus_per_node;
+	cpumask_t node_cpumask;
 
 	node_free_pages =
 #ifdef CONFIG_ZONE_DMA
@@ -41,8 +41,8 @@ static unsigned long max_pages(unsigned 
 
 	max = node_free_pages / FRACTION_OF_NODE_MEM;
 
-	num_cpus_per_node = cpus_weight_nr(node_to_cpumask(node));
-	max /= num_cpus_per_node;
+	node_cpumask = node_to_cpumask(node);
+	max /= cpus_weight_nr(node_cpumask);
 
 	return max(max, min_pages);
 }
_