Re: zone movable patches comments

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 9 Jul 2007 14:21:41 +0100
mel@skynet.ie (Mel Gorman) wrote:
> I'm pretty sure it can be made look nice by changing enum zone_type to
> conditionally define ZONE_MOVABLE and define __GFP_MOVABLE to be 0 when
> it doesn't exist. I'll look at Kame's patch before starting in case it's
> nicer.
> 
This patch is just for sharing idea. I updated mine against 2.6.22-rc6-mm1.
just confirmed my system can boot with this.

Cheers,
-Kame
==
Includes 2 feature.

1. By defining ZONE_xxx even if they are not configured, we can remove many
   ifdefs.
   Instead of #ifdef, is_configurated_zone() func is added.
   compiler will do enough work to inline it and remove unnecessary codes.

2. This patch makes ZONE_MOVABLE to be configurable.

Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 include/linux/gfp.h    |   21 ++++++-------
 include/linux/mmzone.h |   47 ++++++++++++++++--------------
 mm/Kconfig             |   10 ++++++
 mm/page_alloc.c        |   75 +++++++++++++++++++++++++------------------------
 4 files changed, 84 insertions(+), 69 deletions(-)

Index: linux-2.6.22-rc6-mm1/include/linux/mmzone.h
===================================================================
--- linux-2.6.22-rc6-mm1.orig/include/linux/mmzone.h
+++ linux-2.6.22-rc6-mm1/include/linux/mmzone.h
@@ -178,10 +178,33 @@ enum zone_type {
 	 */
 	ZONE_HIGHMEM,
 #endif
+#ifdef CONFIG_ZONE_MOVABLE
 	ZONE_MOVABLE,
-	MAX_NR_ZONES
+#endif
+	MAX_NR_ZONES,
+	/*
+	 * Number for not configured zones.
+	 */
+#ifndef CONFIG_ZONE_DMA
+	ZONE_DMA,
+#endif
+#ifndef CONFIG_ZONE_DMA32
+	ZONE_DMA32,
+#endif
+#ifndef CONFIG_HIGHMEM
+	ZONE_HIGHMEM,
+#endif
+#ifndef CONFIG_ZONE_MOVABLE
+	ZONE_MOVABLE,
+#endif
+	MAX_POSSIBLE_ZONES,
 };
 
+static inline int is_configured_zone(enum zone_type type)
+{
+	return (type < MAX_NR_ZONES);
+}
+
 /*
  * When a memory allocation must conform to specific limitations (such
  * as being suitable for DMA) the caller will pass in hints to the
@@ -200,7 +223,7 @@ enum zone_type {
 	+ defined(CONFIG_ZONE_DMA32)	\
 	+ 1				\
 	+ defined(CONFIG_HIGHMEM)	\
-	+ 1				\
+	+ defined(CONFIG_ZONE_MOVABLE)	\
 )
 #if __ZONE_COUNT < 2
 #define ZONES_SHIFT 0
@@ -546,21 +569,13 @@ extern int movable_zone;
 
 static inline int zone_movable_is_highmem(void)
 {
-#if defined(CONFIG_HIGHMEM) && defined(CONFIG_ARCH_POPULATES_NODE_MAP)
 	return movable_zone == ZONE_HIGHMEM;
-#else
-	return 0;
-#endif
 }
 
 static inline int is_highmem_idx(enum zone_type idx)
 {
-#ifdef CONFIG_HIGHMEM
 	return (idx == ZONE_HIGHMEM ||
 		(idx == ZONE_MOVABLE && zone_movable_is_highmem()));
-#else
-	return 0;
-#endif
 }
 
 static inline int is_normal_idx(enum zone_type idx)
@@ -576,13 +591,9 @@ static inline int is_normal_idx(enum zon
  */
 static inline int is_highmem(struct zone *zone)
 {
-#ifdef CONFIG_HIGHMEM
 	int zone_idx = zone - zone->zone_pgdat->node_zones;
 	return zone_idx == ZONE_HIGHMEM ||
 		(zone_idx == ZONE_MOVABLE && zone_movable_is_highmem());
-#else
-	return 0;
-#endif
 }
 
 static inline int is_normal(struct zone *zone)
@@ -592,20 +603,12 @@ static inline int is_normal(struct zone 
 
 static inline int is_dma32(struct zone *zone)
 {
-#ifdef CONFIG_ZONE_DMA32
 	return zone == zone->zone_pgdat->node_zones + ZONE_DMA32;
-#else
-	return 0;
-#endif
 }
 
 static inline int is_dma(struct zone *zone)
 {
-#ifdef CONFIG_ZONE_DMA
 	return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
-#else
-	return 0;
-#endif
 }
 
 /* These two functions are used to setup the per zone pages min values */
Index: linux-2.6.22-rc6-mm1/include/linux/gfp.h
===================================================================
--- linux-2.6.22-rc6-mm1.orig/include/linux/gfp.h
+++ linux-2.6.22-rc6-mm1/include/linux/gfp.h
@@ -116,21 +116,20 @@ static inline int allocflags_to_migratet
 
 static inline enum zone_type gfp_zone(gfp_t flags)
 {
-#ifdef CONFIG_ZONE_DMA
-	if (flags & __GFP_DMA)
+	if (is_configured_zone(ZONE_DMA) && (flags & __GFP_DMA))
 		return ZONE_DMA;
-#endif
-#ifdef CONFIG_ZONE_DMA32
-	if (flags & __GFP_DMA32)
+
+	if (is_configured_zone(ZONE_DMA32) && (flags & __GFP_DMA32))
 		return ZONE_DMA32;
-#endif
-	if ((flags & (__GFP_HIGHMEM | __GFP_MOVABLE)) ==
-			(__GFP_HIGHMEM | __GFP_MOVABLE))
+
+	if (is_configured_zone(ZONE_MOVABLE) &&
+	    (flags & (__GFP_HIGHMEM | __GFP_MOVABLE)) == (__GFP_HIGHMEM | __GFP_MOVABLE))
+			
 		return ZONE_MOVABLE;
-#ifdef CONFIG_HIGHMEM
-	if (flags & __GFP_HIGHMEM)
+
+	if (is_configured_zone(ZONE_HIGHMEM) && (flags & __GFP_HIGHMEM))
 		return ZONE_HIGHMEM;
-#endif
+
 	return ZONE_NORMAL;
 }
 
Index: linux-2.6.22-rc6-mm1/mm/Kconfig
===================================================================
--- linux-2.6.22-rc6-mm1.orig/mm/Kconfig
+++ linux-2.6.22-rc6-mm1/mm/Kconfig
@@ -112,6 +112,16 @@ config SPARSEMEM_EXTREME
 	def_bool y
 	depends on SPARSEMEM && !SPARSEMEM_STATIC
 
+config ZONE_MOVABLE
+	bool "Create a zone for Movable Pages"
+	depends on ARCH_POPULATES_NODE_MAP
+	help
+	  This option allows you to create a zone only for movable pages.
+	  *movable pages* means which can be target of page migration.
+	  With page migration, you will be able to do "deflag memory" and
+	  "memory unplug". You can do it with usual zones but MOVABLE zones
+	  enables page migration related stuff much easier.
+
 # eventually, we can have this option just 'select SPARSEMEM'
 config MEMORY_HOTPLUG
 	bool "Allow for memory hot-add"
Index: linux-2.6.22-rc6-mm1/mm/page_alloc.c
===================================================================
--- linux-2.6.22-rc6-mm1.orig/mm/page_alloc.c
+++ linux-2.6.22-rc6-mm1/mm/page_alloc.c
@@ -76,35 +76,34 @@ static void __free_pages_ok(struct page 
  *
  * TBD: should special case ZONE_DMA32 machines here - in those we normally
  * don't need any ZONE_NORMAL reservation
+ * see zone_variables_init();
  */
-int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
-#ifdef CONFIG_ZONE_DMA
-	 256,
-#endif
-#ifdef CONFIG_ZONE_DMA32
-	 256,
-#endif
-#ifdef CONFIG_HIGHMEM
-	 32,
-#endif
-	 32,
-};
+int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
 
 EXPORT_SYMBOL(totalram_pages);
 
-static char * const zone_names[MAX_NR_ZONES] = {
-#ifdef CONFIG_ZONE_DMA
-	 "DMA",
-#endif
-#ifdef CONFIG_ZONE_DMA32
-	 "DMA32",
-#endif
-	 "Normal",
-#ifdef CONFIG_HIGHMEM
-	 "HighMem",
-#endif
-	 "Movable",
-};
+static char *zone_names[MAX_POSSIBLE_ZONES];
+static char name_dma[] = "DMA";
+static char name_dma32[] = "DMA32";
+static char name_normal[] = "Normal";
+static char name_highmem[] = "Highmem";
+static char name_movable[] = "Movable";
+
+static inline void __init zone_variables_init(void)
+{
+	zone_names[ZONE_DMA] = name_dma;
+	zone_names[ZONE_DMA32] = name_dma32;
+	zone_names[ZONE_NORMAL] = name_normal;
+	zone_names[ZONE_HIGHMEM] = name_highmem;
+	zone_names[ZONE_MOVABLE] = name_movable;
+	if (is_configured_zone(ZONE_DMA))
+		sysctl_lowmem_reserve_ratio[ZONE_DMA] = 256;
+	if (is_configured_zone(ZONE_DMA32))
+		sysctl_lowmem_reserve_ratio[ZONE_DMA32] = 256;
+	if (is_configured_zone(ZONE_HIGHMEM))
+		sysctl_lowmem_reserve_ratio[ZONE_NORMAL] = 32;
+	/* HIGHMEM and MOVABLE have value 0 */
+}
 
 int min_free_kbytes = 1024;
 
@@ -135,8 +134,8 @@ static unsigned long __meminitdata dma_r
 
   static struct node_active_region __meminitdata early_node_map[MAX_ACTIVE_REGIONS];
   static int __meminitdata nr_nodemap_entries;
-  static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
-  static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
+  static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_POSSIBLE_ZONES];
+  static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_POSSIBLE_ZONES];
 #ifdef CONFIG_MEMORY_HOTPLUG_RESERVE
   static unsigned long __meminitdata node_boundary_start_pfn[MAX_NUMNODES];
   static unsigned long __meminitdata node_boundary_end_pfn[MAX_NUMNODES];
@@ -1835,14 +1834,15 @@ void si_meminfo_node(struct sysinfo *val
 
 	val->totalram = pgdat->node_present_pages;
 	val->freeram = node_page_state(nid, NR_FREE_PAGES);
-#ifdef CONFIG_HIGHMEM
-	val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
-	val->freehigh = zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
+	if (is_configured_zone(ZONE_HIGHMEM)) {
+		val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
+		val->freehigh =
+			zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
 			NR_FREE_PAGES);
-#else
-	val->totalhigh = 0;
-	val->freehigh = 0;
-#endif
+	} else {
+		val->totalhigh = 0;
+		val->freehigh = 0;
+	}
 	val->mem_unit = PAGE_SIZE;
 }
 #endif
@@ -3487,7 +3487,6 @@ void __meminit free_area_init_node(int n
 	calculate_node_totalpages(pgdat, zones_size, zholes_size);
 
 	alloc_node_mem_map(pgdat);
-
 	free_area_init_core(pgdat, zones_size, zholes_size);
 }
 
@@ -3871,6 +3870,7 @@ void __init free_area_init_nodes(unsigne
 						early_node_map[i].end_pfn);
 
 	/* Initialise every node */
+	zone_variables_init();
 	setup_nr_node_ids();
 	for_each_online_node(nid) {
 		pg_data_t *pgdat = NODE_DATA(nid);
@@ -3888,7 +3888,9 @@ static int __init cmdline_parse_kernelco
 	unsigned long long coremem;
 	if (!p)
 		return -EINVAL;
-
+	/* can we use ZONE_MOVABLE ? */
+	if (!is_configured_zone(ZONE_MOVABLE))
+		return 0;
 	coremem = memparse(p, &p);
 	required_kernelcore = coremem >> PAGE_SHIFT;
 
@@ -3927,6 +3929,7 @@ EXPORT_SYMBOL(contig_page_data);
 
 void __init free_area_init(unsigned long *zones_size)
 {
+	zone_variables_init();
 	free_area_init_node(0, NODE_DATA(0), zones_size,
 			__pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
 }


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