[PATCH v3] Add populated_map to account for memoryless nodes

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 11.06.2007 [15:42:37 -0700], Christoph Lameter wrote:
> On Mon, 11 Jun 2007, Nishanth Aravamudan wrote:
> 
> > Already done in the original patch (node_populated() returns (node == 0)
> > if MAX_NUMODES <= 1), I think.
> 
> Ah good.
> 
> > @@ -2299,6 +2303,18 @@ static void build_zonelists(pg_data_t *pgdat)
> >  		/* calculate node order -- i.e., DMA last! */
> >  		build_zonelists_in_zone_order(pgdat, j);
> >  	}
> > +
> > +	/*
> > +	 * record nodes whose first fallback zone is "on-node" as
> > +	 * populated
> > +	 */
> > +	z = pgdat->node_zonelists->zones[0];
> > +
> > +	VM_BUG_ON(!z);
> > +	if (z->zone_pgdat == pgdat)
> > +		node_set_populated(local_node);
> > +	else
> > +		node_not_populated(local_node);
> >  }
> >  
> >  /* Construct the zonelist performance cache - see further mmzone.h */
> > 
> 
> Could be much simpler:
> 
> if (pgdat->node_present_pages)
> 	node_set_populated(local_node);

Err, duh -- I was thinking of making this change, but then forgot.

Thanks for the reviews, Christoph!

Split up Lee and Anton's original patch
(http://marc.info/?l=linux-mm&m=118133042025995&w=2), to allow for the
populated_map changes to go in on their own.

Add a populated_map nodemask to indicate a node has memory or not. We
have run into a number of issues (in practice and in code) with
assumptions about every node having memory. Having this nodemask allows
us to fix these issues; in particular, THISNODE allocations will come
from the node specified, only, and the INTERLEAVE policy will be able to
do the right thing with memoryless nodes.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>

diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 52c54a5..c00a249 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -64,12 +64,16 @@
  *
  * int node_online(node)		Is some node online?
  * int node_possible(node)		Is some node possible?
+ * int node_populated(node)		Is some node populated?
  *
  * int any_online_node(mask)		First online node in mask
  *
  * node_set_online(node)		set bit 'node' in node_online_map
  * node_set_offline(node)		clear bit 'node' in node_online_map
  *
+ * node_set_populated(node)		set bit 'node' in node_populated_map
+ * node_not_populated(node)		clear bit 'node' in node_populated_map
+ *
  * for_each_node(node)			for-loop node over node_possible_map
  * for_each_online_node(node)		for-loop node over node_online_map
  *
@@ -344,12 +348,14 @@ static inline void __nodes_remap(nodemask_t *dstp, const nodemask_t *srcp,
 
 extern nodemask_t node_online_map;
 extern nodemask_t node_possible_map;
+extern nodemask_t node_populated_map;
 
 #if MAX_NUMNODES > 1
 #define num_online_nodes()	nodes_weight(node_online_map)
 #define num_possible_nodes()	nodes_weight(node_possible_map)
 #define node_online(node)	node_isset((node), node_online_map)
 #define node_possible(node)	node_isset((node), node_possible_map)
+#define node_populated(node)	node_isset((node), node_populated_map)
 #define first_online_node	first_node(node_online_map)
 #define next_online_node(nid)	next_node((nid), node_online_map)
 extern int nr_node_ids;
@@ -358,6 +364,7 @@ extern int nr_node_ids;
 #define num_possible_nodes()	1
 #define node_online(node)	((node) == 0)
 #define node_possible(node)	((node) == 0)
+#define node_populated(node)	((node) == 0)
 #define first_online_node	0
 #define next_online_node(nid)	(MAX_NUMNODES)
 #define nr_node_ids		1
@@ -375,6 +382,9 @@ extern int nr_node_ids;
 #define node_set_online(node)	   set_bit((node), node_online_map.bits)
 #define node_set_offline(node)	   clear_bit((node), node_online_map.bits)
 
+#define node_set_populated(node)   set_bit((node), node_populated_map.bits)
+#define node_not_populated(node)   clear_bit((node), node_populated_map.bits)
+
 #define for_each_node(node)	   for_each_node_mask((node), node_possible_map)
 #define for_each_online_node(node) for_each_node_mask((node), node_online_map)
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 07cd5ae..456f2f6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -54,6 +54,9 @@ nodemask_t node_online_map __read_mostly = { { [0] = 1UL } };
 EXPORT_SYMBOL(node_online_map);
 nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL;
 EXPORT_SYMBOL(node_possible_map);
+nodemask_t node_populated_map __read_mostly = NODE_MASK_NONE;
+EXPORT_SYMBOL(node_populated_map);
+
 unsigned long totalram_pages __read_mostly;
 unsigned long totalreserve_pages __read_mostly;
 long nr_swap_pages;
@@ -2299,6 +2302,13 @@ static void build_zonelists(pg_data_t *pgdat)
 		/* calculate node order -- i.e., DMA last! */
 		build_zonelists_in_zone_order(pgdat, j);
 	}
+
+	/*
+	 * record populated zones for use when INTERLEAVE'ing or using
+	 * GFP_THISNODE
+	 */
+	if (pgdat->node_present_pages)
+		node_set_populated(local_node);
 }
 
 /* Construct the zonelist performance cache - see further mmzone.h */

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