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-rw-r--r--include/linux/compaction.h9
-rw-r--r--include/linux/migrate.h2
-rw-r--r--include/linux/mm.h1
-rw-r--r--include/linux/swap.h1
-rw-r--r--include/linux/vmstat.h3
-rw-r--r--mm/Makefile1
-rw-r--r--mm/compaction.c393
-rw-r--r--mm/migrate.c11
-rw-r--r--mm/page_alloc.c45
-rw-r--r--mm/vmstat.c7
10 files changed, 472 insertions, 1 deletions
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
new file mode 100644
index 0000000..465ca88
--- /dev/null
+++ b/include/linux/compaction.h
@@ -0,0 +1,9 @@
+#ifndef _LINUX_COMPACTION_H
+#define _LINUX_COMPACTION_H
+
+/* Return values for compact_zone() */
+#define COMPACT_CONTINUE 0
+#define COMPACT_PARTIAL 1
+#define COMPACT_COMPLETE 2
+
+#endif /* _LINUX_COMPACTION_H */
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 7a07b17..7238231 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -19,6 +19,7 @@ extern int fail_migrate_page(struct address_space *,
struct page *, struct page *);
extern int migrate_prep(void);
+extern int migrate_prep_local(void);
extern int migrate_vmas(struct mm_struct *mm,
const nodemask_t *from, const nodemask_t *to,
unsigned long flags);
@@ -30,6 +31,7 @@ static inline int migrate_pages(struct list_head *l, new_page_t x,
unsigned long private, int offlining) { return -ENOSYS; }
static inline int migrate_prep(void) { return -ENOSYS; }
+static inline int migrate_prep_local(void) { return -ENOSYS; }
static inline int migrate_vmas(struct mm_struct *mm,
const nodemask_t *from, const nodemask_t *to,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 98ea5ba..963f908 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -337,6 +337,7 @@ void put_page(struct page *page);
void put_pages_list(struct list_head *pages);
void split_page(struct page *page, unsigned int order);
+int split_free_page(struct page *page);
/*
* Compound pages have a destructor function. Provide a
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 1e8ce14..b6b6143 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -152,6 +152,7 @@ enum {
};
#define SWAP_CLUSTER_MAX 32
+#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 117f0dd..b421d1b 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -43,6 +43,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
KSWAPD_SKIP_CONGESTION_WAIT,
PAGEOUTRUN, ALLOCSTALL, PGROTATED,
+#ifdef CONFIG_COMPACTION
+ COMPACTBLOCKS, COMPACTPAGES, COMPACTPAGEFAILED,
+#endif
#ifdef CONFIG_HUGETLB_PAGE
HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
#endif
diff --git a/mm/Makefile b/mm/Makefile
index 6c2a73a..8982504 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_NUMA) += mempolicy.o
obj-$(CONFIG_SPARSEMEM) += sparse.o
obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
obj-$(CONFIG_SLOB) += slob.o
+obj-$(CONFIG_COMPACTION) += compaction.o
obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
obj-$(CONFIG_KSM) += ksm.o
obj-$(CONFIG_PAGE_POISONING) += debug-pagealloc.o
diff --git a/mm/compaction.c b/mm/compaction.c
new file mode 100644
index 0000000..be1ff3f
--- /dev/null
+++ b/mm/compaction.c
@@ -0,0 +1,393 @@
+/*
+ * linux/mm/compaction.c
+ *
+ * Memory compaction for the reduction of external fragmentation. Note that
+ * this heavily depends upon page migration to do all the real heavy
+ * lifting
+ *
+ * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
+ */
+#include <linux/swap.h>
+#include <linux/migrate.h>
+#include <linux/compaction.h>
+#include <linux/mm_inline.h>
+#include <linux/backing-dev.h>
+#include "internal.h"
+
+/*
+ * compact_control is used to track pages being migrated and the free pages
+ * they are being migrated to during memory compaction. The free_pfn starts
+ * at the end of a zone and migrate_pfn begins at the start. Movable pages
+ * are moved to the end of a zone during a compaction run and the run
+ * completes when free_pfn <= migrate_pfn
+ */
+struct compact_control {
+ struct list_head freepages; /* List of free pages to migrate to */
+ struct list_head migratepages; /* List of pages being migrated */
+ unsigned long nr_freepages; /* Number of isolated free pages */
+ unsigned long nr_migratepages; /* Number of pages to migrate */
+ unsigned long free_pfn; /* isolate_freepages search base */
+ unsigned long migrate_pfn; /* isolate_migratepages search base */
+
+ /* Account for isolated anon and file pages */
+ unsigned long nr_anon;
+ unsigned long nr_file;
+
+ struct zone *zone;
+};
+
+static unsigned long release_freepages(struct list_head *freelist)
+{
+ struct page *page, *next;
+ unsigned long count = 0;
+
+ list_for_each_entry_safe(page, next, freelist, lru) {
+ list_del(&page->lru);
+ __free_page(page);
+ count++;
+ }
+
+ return count;
+}
+
+/* Isolate free pages onto a private freelist. Must hold zone->lock */
+static unsigned long isolate_freepages_block(struct zone *zone,
+ unsigned long blockpfn,
+ struct list_head *freelist)
+{
+ unsigned long zone_end_pfn, end_pfn;
+ int total_isolated = 0;
+ struct page *cursor;
+
+ /* Get the last PFN we should scan for free pages at */
+ zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
+ end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn);
+
+ /* Find the first usable PFN in the block to initialse page cursor */
+ for (; blockpfn < end_pfn; blockpfn++) {
+ if (pfn_valid_within(blockpfn))
+ break;
+ }
+ cursor = pfn_to_page(blockpfn);
+
+ /* Isolate free pages. This assumes the block is valid */
+ for (; blockpfn < end_pfn; blockpfn++, cursor++) {
+ int isolated, i;
+ struct page *page = cursor;
+
+ if (!pfn_valid_within(blockpfn))
+ continue;
+
+ if (!PageBuddy(page))
+ continue;
+
+ /* Found a free page, break it into order-0 pages */
+ isolated = split_free_page(page);
+ total_isolated += isolated;
+ for (i = 0; i < isolated; i++) {
+ list_add(&page->lru, freelist);
+ page++;
+ }
+
+ /* If a page was split, advance to the end of it */
+ if (isolated) {
+ blockpfn += isolated - 1;
+ cursor += isolated - 1;
+ }
+ }
+
+ return total_isolated;
+}
+
+/* Returns true if the page is within a block suitable for migration to */
+static bool suitable_migration_target(struct page *page)
+{
+
+ int migratetype = get_pageblock_migratetype(page);
+
+ /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
+ if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
+ return false;
+
+ /* If the page is a large free page, then allow migration */
+ if (PageBuddy(page) && page_order(page) >= pageblock_order)
+ return true;
+
+ /* If the block is MIGRATE_MOVABLE, allow migration */
+ if (migratetype == MIGRATE_MOVABLE)
+ return true;
+
+ /* Otherwise skip the block */
+ return false;
+}
+
+/*
+ * Based on information in the current compact_control, find blocks
+ * suitable for isolating free pages from and then isolate them.
+ */
+static void isolate_freepages(struct zone *zone,
+ struct compact_control *cc)
+{
+ struct page *page;
+ unsigned long high_pfn, low_pfn, pfn;
+ unsigned long flags;
+ int nr_freepages = cc->nr_freepages;
+ struct list_head *freelist = &cc->freepages;
+
+ pfn = cc->free_pfn;
+ low_pfn = cc->migrate_pfn + pageblock_nr_pages;
+ high_pfn = low_pfn;
+
+ /*
+ * Isolate free pages until enough are available to migrate the
+ * pages on cc->migratepages. We stop searching if the migrate
+ * and free page scanners meet or enough free pages are isolated.
+ */
+ spin_lock_irqsave(&zone->lock, flags);
+ for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
+ pfn -= pageblock_nr_pages) {
+ unsigned long isolated;
+
+ if (!pfn_valid(pfn))
+ continue;
+
+ /*
+ * Check for overlapping nodes/zones. It's possible on some
+ * configurations to have a setup like
+ * node0 node1 node0
+ * i.e. it's possible that all pages within a zones range of
+ * pages do not belong to a single zone.
+ */
+ page = pfn_to_page(pfn);
+ if (page_zone(page) != zone)
+ continue;
+
+ /* Check the block is suitable for migration */
+ if (!suitable_migration_target(page))
+ continue;
+
+ /* Found a block suitable for isolating free pages from */
+ isolated = isolate_freepages_block(zone, pfn, freelist);
+ nr_freepages += isolated;
+
+ /*
+ * Record the highest PFN we isolated pages from. When next
+ * looking for free pages, the search will restart here as
+ * page migration may have returned some pages to the allocator
+ */
+ if (isolated)
+ high_pfn = max(high_pfn, pfn);
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ /* split_free_page does not map the pages */
+ list_for_each_entry(page, freelist, lru) {
+ arch_alloc_page(page, 0);
+ kernel_map_pages(page, 1, 1);
+ }
+
+ cc->free_pfn = high_pfn;
+ cc->nr_freepages = nr_freepages;
+}
+
+/* Update the number of anon and file isolated pages in the zone */
+static void acct_isolated(struct zone *zone, struct compact_control *cc)
+{
+ struct page *page;
+ unsigned int count[NR_LRU_LISTS] = { 0, };
+
+ list_for_each_entry(page, &cc->migratepages, lru) {
+ int lru = page_lru_base_type(page);
+ count[lru]++;
+ }
+
+ cc->nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
+ cc->nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
+ __mod_zone_page_state(zone, NR_ISOLATED_ANON, cc->nr_anon);
+ __mod_zone_page_state(zone, NR_ISOLATED_FILE, cc->nr_file);
+}
+
+/* Similar to reclaim, but different enough that they don't share logic */
+static bool too_many_isolated(struct zone *zone)
+{
+
+ unsigned long inactive, isolated;
+
+ inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
+ zone_page_state(zone, NR_INACTIVE_ANON);
+ isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
+ zone_page_state(zone, NR_ISOLATED_ANON);
+
+ return isolated > inactive;
+}
+
+/*
+ * Isolate all pages that can be migrated from the block pointed to by
+ * the migrate scanner within compact_control.
+ */
+static unsigned long isolate_migratepages(struct zone *zone,
+ struct compact_control *cc)
+{
+ unsigned long low_pfn, end_pfn;
+ struct list_head *migratelist = &cc->migratepages;
+
+ /* Do not scan outside zone boundaries */
+ low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
+
+ /* Only scan within a pageblock boundary */
+ end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
+
+ /* Do not cross the free scanner or scan within a memory hole */
+ if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
+ cc->migrate_pfn = end_pfn;
+ return 0;
+ }
+
+ /*
+ * Ensure that there are not too many pages isolated from the LRU
+ * list by either parallel reclaimers or compaction. If there are,
+ * delay for some time until fewer pages are isolated
+ */
+ while (unlikely(too_many_isolated(zone))) {
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
+
+ if (fatal_signal_pending(current))
+ return 0;
+ }
+
+ /* Time to isolate some pages for migration */
+ spin_lock_irq(&zone->lru_lock);
+ for (; low_pfn < end_pfn; low_pfn++) {
+ struct page *page;
+ if (!pfn_valid_within(low_pfn))
+ continue;
+
+ /* Get the page and skip if free */
+ page = pfn_to_page(low_pfn);
+ if (PageBuddy(page))
+ continue;
+
+ /* Try isolate the page */
+ if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
+ continue;
+
+ /* Successfully isolated */
+ del_page_from_lru_list(zone, page, page_lru(page));
+ list_add(&page->lru, migratelist);
+ mem_cgroup_del_lru(page);
+ cc->nr_migratepages++;
+
+ /* Avoid isolating too much */
+ if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
+ break;
+ }
+
+ acct_isolated(zone, cc);
+
+ spin_unlock_irq(&zone->lru_lock);
+ cc->migrate_pfn = low_pfn;
+
+ return cc->nr_migratepages;
+}
+
+/*
+ * This is a migrate-callback that "allocates" freepages by taking pages
+ * from the isolated freelists in the block we are migrating to.
+ */
+static struct page *compaction_alloc(struct page *migratepage,
+ unsigned long data,
+ int **result)
+{
+ struct compact_control *cc = (struct compact_control *)data;
+ struct page *freepage;
+
+ /* Isolate free pages if necessary */
+ if (list_empty(&cc->freepages)) {
+ isolate_freepages(cc->zone, cc);
+
+ if (list_empty(&cc->freepages))
+ return NULL;
+ }
+
+ freepage = list_entry(cc->freepages.next, struct page, lru);
+ list_del(&freepage->lru);
+ cc->nr_freepages--;
+
+ return freepage;
+}
+
+/*
+ * We cannot control nr_migratepages and nr_freepages fully when migration is
+ * running as migrate_pages() has no knowledge of compact_control. When
+ * migration is complete, we count the number of pages on the lists by hand.
+ */
+static void update_nr_listpages(struct compact_control *cc)
+{
+ int nr_migratepages = 0;
+ int nr_freepages = 0;
+ struct page *page;
+
+ list_for_each_entry(page, &cc->migratepages, lru)
+ nr_migratepages++;
+ list_for_each_entry(page, &cc->freepages, lru)
+ nr_freepages++;
+
+ cc->nr_migratepages = nr_migratepages;
+ cc->nr_freepages = nr_freepages;
+}
+
+static int compact_finished(struct zone *zone,
+ struct compact_control *cc)
+{
+ if (fatal_signal_pending(current))
+ return COMPACT_PARTIAL;
+
+ /* Compaction run completes if the migrate and free scanner meet */
+ if (cc->free_pfn <= cc->migrate_pfn)
+ return COMPACT_COMPLETE;
+
+ return COMPACT_CONTINUE;
+}
+
+static int compact_zone(struct zone *zone, struct compact_control *cc)
+{
+ int ret;
+
+ /* Setup to move all movable pages to the end of the zone */
+ cc->migrate_pfn = zone->zone_start_pfn;
+ cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
+ cc->free_pfn &= ~(pageblock_nr_pages-1);
+
+ migrate_prep_local();
+
+ while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
+ unsigned long nr_migrate, nr_remaining;
+
+ if (!isolate_migratepages(zone, cc))
+ continue;
+
+ nr_migrate = cc->nr_migratepages;
+ migrate_pages(&cc->migratepages, compaction_alloc,
+ (unsigned long)cc, 0);
+ update_nr_listpages(cc);
+ nr_remaining = cc->nr_migratepages;
+
+ count_vm_event(COMPACTBLOCKS);
+ count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining);
+ if (nr_remaining)
+ count_vm_events(COMPACTPAGEFAILED, nr_remaining);
+
+ /* Release LRU pages not migrated */
+ if (!list_empty(&cc->migratepages)) {
+ putback_lru_pages(&cc->migratepages);
+ cc->nr_migratepages = 0;
+ }
+
+ }
+
+ /* Release free pages and check accounting */
+ cc->nr_freepages -= release_freepages(&cc->freepages);
+ VM_BUG_ON(cc->nr_freepages != 0);
+
+ return ret;
+}
diff --git a/mm/migrate.c b/mm/migrate.c
index 4afd6fe..09e2471 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -40,7 +40,8 @@
/*
* migrate_prep() needs to be called before we start compiling a list of pages
- * to be migrated using isolate_lru_page().
+ * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
+ * undesirable, use migrate_prep_local()
*/
int migrate_prep(void)
{
@@ -55,6 +56,14 @@ int migrate_prep(void)
return 0;
}
+/* Do the necessary work of migrate_prep but not if it involves other CPUs */
+int migrate_prep_local(void)
+{
+ lru_add_drain();
+
+ return 0;
+}
+
/*
* Add isolated pages on the list back to the LRU under page lock
* to avoid leaking evictable pages back onto unevictable list.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cefe6fe..c54376a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1208,6 +1208,51 @@ void split_page(struct page *page, unsigned int order)
}
/*
+ * Similar to split_page except the page is already free. As this is only
+ * being used for migration, the migratetype of the block also changes.
+ * As this is called with interrupts disabled, the caller is responsible
+ * for calling arch_alloc_page() and kernel_map_page() after interrupts
+ * are enabled.
+ *
+ * Note: this is probably too low level an operation for use in drivers.
+ * Please consult with lkml before using this in your driver.
+ */
+int split_free_page(struct page *page)
+{
+ unsigned int order;
+ unsigned long watermark;
+ struct zone *zone;
+
+ BUG_ON(!PageBuddy(page));
+
+ zone = page_zone(page);
+ order = page_order(page);
+
+ /* Obey watermarks as if the page was being allocated */
+ watermark = low_wmark_pages(zone) + (1 << order);
+ if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
+ return 0;
+
+ /* Remove page from free list */
+ list_del(&page->lru);
+ zone->free_area[order].nr_free--;
+ rmv_page_order(page);
+ __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
+
+ /* Split into individual pages */
+ set_page_refcounted(page);
+ split_page(page, order);
+
+ if (order >= pageblock_order - 1) {
+ struct page *endpage = page + (1 << order) - 1;
+ for (; page < endpage; page += pageblock_nr_pages)
+ set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+ }
+
+ return 1 << order;
+}
+
+/*
* Really, prep_compound_page() should be called from __rmqueue_bulk(). But
* we cheat by calling it from here, in the order > 0 path. Saves a branch
* or two.
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 23a5899..c6aacf5 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -766,6 +766,13 @@ static const char * const vmstat_text[] = {
"allocstall",
"pgrotated",
+
+#ifdef CONFIG_COMPACTION
+ "compact_blocks_moved",
+ "compact_pages_moved",
+ "compact_pagemigrate_failed",
+#endif
+
#ifdef CONFIG_HUGETLB_PAGE
"htlb_buddy_alloc_success",
"htlb_buddy_alloc_fail",
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