[PATCH 3/5] Light Fragmentation Avoidance V20: 003_fragcore
From: Mel Gorman
Date: Tue Nov 15 2005 - 11:50:38 EST
This patch adds the core of the anti-fragmentation strategy. It works by
grouping related allocation types together. The idea is that large groups of
pages that may be reclaimed are placed near each other. The zone->free_area
list is broken into RCLM_TYPES number of lists.
Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
diff -rup -X /usr/src/patchset-0.5/bin//dontdiff linux-2.6.14-mm2-002_usemap/include/linux/mmzone.h linux-2.6.14-mm2-003_fragcore/include/linux/mmzone.h
--- linux-2.6.14-mm2-002_usemap/include/linux/mmzone.h 2005-11-15 12:42:15.000000000 +0000
+++ linux-2.6.14-mm2-003_fragcore/include/linux/mmzone.h 2005-11-15 12:43:41.000000000 +0000
@@ -27,6 +27,12 @@
#define RCLM_EASY 1
#define RCLM_TYPES 2
+#define for_each_rclmtype(type) \
+ for (type = 0; type < RCLM_TYPES; type++)
+#define for_each_rclmtype_order(type, order) \
+ for (order = 0; order < MAX_ORDER; order++) \
+ for (type = 0; type < RCLM_TYPES; type++)
+
struct free_area {
struct list_head free_list;
unsigned long nr_free;
@@ -150,7 +156,7 @@ struct zone {
/* see spanned/present_pages for more description */
seqlock_t span_seqlock;
#endif
- struct free_area free_area[MAX_ORDER];
+ struct free_area free_area_lists[RCLM_TYPES][MAX_ORDER];
#ifndef CONFIG_SPARSEMEM
/*
diff -rup -X /usr/src/patchset-0.5/bin//dontdiff linux-2.6.14-mm2-002_usemap/mm/page_alloc.c linux-2.6.14-mm2-003_fragcore/mm/page_alloc.c
--- linux-2.6.14-mm2-002_usemap/mm/page_alloc.c 2005-11-15 12:42:15.000000000 +0000
+++ linux-2.6.14-mm2-003_fragcore/mm/page_alloc.c 2005-11-15 12:44:27.000000000 +0000
@@ -68,6 +68,11 @@ int sysctl_lowmem_reserve_ratio[MAX_NR_Z
EXPORT_SYMBOL(totalram_pages);
+static inline int gfpflags_to_alloctype(unsigned long gfp_flags)
+{
+ return ((gfp_flags & __GFP_EASYRCLM) != 0);
+}
+
static inline int get_pageblock_type(struct zone *zone, struct page *page)
{
unsigned long pfn = page_to_pfn(page);
@@ -272,6 +277,16 @@ __find_combined_index(unsigned long page
}
/*
+ * Return the free list for a given page within a zone
+ */
+static inline struct free_area *__page_find_freelist(struct zone *zone,
+ struct page *page,
+ int order)
+{
+ return &zone->free_area_lists[get_pageblock_type(zone, page)][order];
+}
+
+/*
* This function checks whether a page is free && is the buddy
* we can do coalesce a page and its buddy if
* (a) the buddy is free &&
@@ -318,6 +333,7 @@ static inline void __free_pages_bulk (st
{
unsigned long page_idx;
int order_size = 1 << order;
+ struct free_area *freelist;
if (unlikely(order))
destroy_compound_page(page, order);
@@ -327,10 +343,11 @@ static inline void __free_pages_bulk (st
BUG_ON(page_idx & (order_size - 1));
BUG_ON(bad_range(zone, page));
+ freelist = __page_find_freelist(zone, page, order);
+
zone->free_pages += order_size;
while (order < MAX_ORDER-1) {
unsigned long combined_idx;
- struct free_area *area;
struct page *buddy;
combined_idx = __find_combined_index(page_idx, order);
@@ -341,16 +358,16 @@ static inline void __free_pages_bulk (st
if (!page_is_buddy(buddy, order))
break; /* Move the buddy up one level. */
list_del(&buddy->lru);
- area = zone->free_area + order;
- area->nr_free--;
+ freelist->nr_free--;
rmv_page_order(buddy);
page = page + (combined_idx - page_idx);
page_idx = combined_idx;
order++;
+ freelist++;
}
set_page_order(page, order);
- list_add(&page->lru, &zone->free_area[order].free_list);
- zone->free_area[order].nr_free++;
+ list_add(&page->lru, &freelist->free_list);
+ freelist->nr_free++;
}
static inline void free_pages_check(const char *function, struct page *page)
@@ -507,18 +524,59 @@ static void prep_new_page(struct page *p
kernel_map_pages(page, 1 << order, 1);
}
+/* Remove an element from the buddy allocator from the fallback list */
+static struct page *__rmqueue_fallback(struct zone *zone, int order,
+ int alloctype)
+{
+ struct free_area * area;
+ int current_order;
+ struct page *page;
+
+ /* Find the largest possible block of pages in the other list */
+ alloctype = !alloctype;
+ for (current_order = MAX_ORDER-1; current_order >= order;
+ --current_order) {
+ area = &(zone->free_area_lists[alloctype][current_order]);
+ if (list_empty(&area->free_list))
+ continue;
+
+ page = list_entry(area->free_list.next, struct page, lru);
+ area->nr_free--;
+
+ /*
+ * If breaking a large block of pages, place the buddies
+ * on the preferred allocation list
+ */
+ if (unlikely(current_order >= MAX_ORDER / 2)) {
+ alloctype = !alloctype;
+ change_pageblock_type(zone, page);
+ area = &zone->free_area_lists[alloctype][current_order];
+ }
+
+ list_del(&page->lru);
+ rmv_page_order(page);
+ zone->free_pages -= 1UL << order;
+ return expand(zone, page, order, current_order, area);
+
+ }
+
+ return NULL;
+}
+
/*
* Do the hard work of removing an element from the buddy allocator.
* Call me with the zone->lock already held.
*/
-static struct page *__rmqueue(struct zone *zone, unsigned int order)
+static struct page *__rmqueue(struct zone *zone, unsigned int order,
+ int alloctype)
{
struct free_area * area;
unsigned int current_order;
struct page *page;
+ /* Find a page of the appropriate size in the preferred list */
for (current_order = order; current_order < MAX_ORDER; ++current_order) {
- area = zone->free_area + current_order;
+ area = &(zone->free_area_lists[alloctype][current_order]);
if (list_empty(&area->free_list))
continue;
@@ -530,16 +588,18 @@ static struct page *__rmqueue(struct zon
return expand(zone, page, order, current_order, area);
}
- return NULL;
+ return __rmqueue_fallback(zone, order, alloctype);
}
+
/*
* Obtain a specified number of elements from the buddy allocator, all under
* a single hold of the lock, for efficiency. Add them to the supplied list.
* Returns the number of new pages which were placed at *list.
*/
static int rmqueue_bulk(struct zone *zone, unsigned int order,
- unsigned long count, struct list_head *list)
+ unsigned long count, struct list_head *list,
+ int alloctype)
{
unsigned long flags;
int i;
@@ -548,7 +608,7 @@ static int rmqueue_bulk(struct zone *zon
spin_lock_irqsave(&zone->lock, flags);
for (i = 0; i < count; ++i) {
- page = __rmqueue(zone, order);
+ page = __rmqueue(zone, order, alloctype);
if (page == NULL)
break;
allocated++;
@@ -614,7 +674,7 @@ static void __drain_pages(unsigned int c
void mark_free_pages(struct zone *zone)
{
unsigned long zone_pfn, flags;
- int order;
+ int order, t;
struct list_head *curr;
if (!zone->spanned_pages)
@@ -624,14 +684,13 @@ void mark_free_pages(struct zone *zone)
for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
ClearPageNosaveFree(pfn_to_page(zone_pfn + zone->zone_start_pfn));
- for (order = MAX_ORDER - 1; order >= 0; --order)
- list_for_each(curr, &zone->free_area[order].free_list) {
+ for_each_rclmtype_order(t, order) {
+ list_for_each(curr,&zone->free_area_lists[t][order].free_list) {
unsigned long start_pfn, i;
-
start_pfn = page_to_pfn(list_entry(curr, struct page, lru));
-
for (i=0; i < (1<<order); i++)
SetPageNosaveFree(pfn_to_page(start_pfn+i));
+ }
}
spin_unlock_irqrestore(&zone->lock, flags);
}
@@ -732,6 +791,7 @@ buffered_rmqueue(struct zone *zone, int
unsigned long flags;
struct page *page = NULL;
int cold = !!(gfp_flags & __GFP_COLD);
+ int alloctype = gfpflags_to_alloctype(gfp_flags);
if (order == 0) {
struct per_cpu_pages *pcp;
@@ -740,7 +800,8 @@ buffered_rmqueue(struct zone *zone, int
local_irq_save(flags);
if (pcp->count <= pcp->low)
pcp->count += rmqueue_bulk(zone, 0,
- pcp->batch, &pcp->list);
+ pcp->batch, &pcp->list,
+ alloctype);
if (pcp->count) {
page = list_entry(pcp->list.next, struct page, lru);
list_del(&page->lru);
@@ -750,7 +811,7 @@ buffered_rmqueue(struct zone *zone, int
put_cpu();
} else {
spin_lock_irqsave(&zone->lock, flags);
- page = __rmqueue(zone, order);
+ page = __rmqueue(zone, order, alloctype);
spin_unlock_irqrestore(&zone->lock, flags);
}
@@ -781,25 +842,32 @@ int zone_watermark_ok(struct zone *z, in
int classzone_idx, int alloc_flags)
{
/* free_pages my go negative - that's OK */
- long min = mark, free_pages = z->free_pages - (1 << order) + 1;
- int o;
+ long free_pages = z->free_pages - (1 << order) + 1;
+ long min;
+ int o,t;
if (alloc_flags & ALLOC_HIGH)
- min -= min / 2;
+ mark -= mark / 2;
if (alloc_flags & ALLOC_HARDER)
- min -= min / 4;
+ mark -= mark / 4;
- if (free_pages <= min + z->lowmem_reserve[classzone_idx])
+ if (free_pages <= mark + z->lowmem_reserve[classzone_idx])
goto out_failed;
- for (o = 0; o < order; o++) {
- /* At the next order, this order's pages become unavailable */
- free_pages -= z->free_area[o].nr_free << o;
+ for_each_rclmtype(t) {
+ min = mark;
+ for (o = 0; o < order; o++) {
+ /*
+ * At the next order, this order's pages become
+ * unavailable
+ */
+ free_pages -= z->free_area_lists[t][o].nr_free << o;
- /* Require fewer higher order pages to be free */
- min >>= 1;
+ /* Require fewer higher order pages to be free */
+ min >>= 1;
- if (free_pages <= min)
- goto out_failed;
+ if (free_pages <= min)
+ goto out_failed;
+ }
}
return 1;
@@ -1380,6 +1448,7 @@ void show_free_areas(void)
unsigned long inactive;
unsigned long free;
struct zone *zone;
+ int type;
for_each_zone(zone) {
show_node(zone);
@@ -1459,7 +1528,9 @@ void show_free_areas(void)
}
for_each_zone(zone) {
- unsigned long nr, flags, order, total = 0;
+ unsigned long nr = 0;
+ unsigned long total = 0;
+ unsigned long flags,order;
show_node(zone);
printk("%s: ", zone->name);
@@ -1469,10 +1540,18 @@ void show_free_areas(void)
}
spin_lock_irqsave(&zone->lock, flags);
- for (order = 0; order < MAX_ORDER; order++) {
- nr = zone->free_area[order].nr_free;
+ for_each_rclmtype_order(type, order) {
+ nr += zone->free_area_lists[type][order].nr_free;
total += nr << order;
- printk("%lu*%lukB ", nr, K(1UL) << order);
+
+ /*
+ * If type had reached RCLM_TYPE, the free pages
+ * for this order have been summed up
+ */
+ if (type == RCLM_TYPES-1) {
+ printk("%lu*%lukB ", nr, K(1UL) << order);
+ nr = 0;
+ }
}
spin_unlock_irqrestore(&zone->lock, flags);
printk("= %lukB\n", K(total));
@@ -1782,9 +1861,14 @@ void zone_init_free_lists(struct pglist_
unsigned long size)
{
int order;
- for (order = 0; order < MAX_ORDER ; order++) {
- INIT_LIST_HEAD(&zone->free_area[order].free_list);
- zone->free_area[order].nr_free = 0;
+ int type;
+ struct free_area *area;
+
+ /* Initialse the three size ordered lists of free_areas */
+ for_each_rclmtype_order(type, order) {
+ area = &(zone->free_area_lists[type][order]);
+ INIT_LIST_HEAD(&area->free_list);
+ area->nr_free = 0;
}
}
@@ -2199,16 +2283,26 @@ static int frag_show(struct seq_file *m,
struct zone *zone;
struct zone *node_zones = pgdat->node_zones;
unsigned long flags;
- int order;
+ int order, t;
+ struct free_area *area;
+ unsigned long nr_bufs = 0;
for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
if (!zone->present_pages)
continue;
spin_lock_irqsave(&zone->lock, flags);
- seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
- for (order = 0; order < MAX_ORDER; ++order)
- seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
+ seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
+ for_each_rclmtype_order(t, order) {
+ area = &(zone->free_area_lists[t][order]);
+ nr_bufs += area->nr_free;
+
+ if (t == RCLM_TYPES-1) {
+ seq_printf(m, "%6lu ", nr_bufs);
+ nr_bufs = 0;
+ }
+ }
+
spin_unlock_irqrestore(&zone->lock, flags);
seq_putc(m, '\n');
}
-
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