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;
+ bool sync; /* Synchronous migration */
unsigned int order; /* order a direct compactor needs */
int migratetype; /* MOVABLE, RECLAIMABLE etc */
int nr_freepages = cc->nr_freepages;
struct list_head *freelist = &cc->freepages;
+ /*
+ * Initialise the free scanner. The starting point is where we last
+ * scanned from (or the end of the zone if starting). The low point
+ * is the end of the pageblock the migration scanner is using.
+ */
pfn = cc->free_pfn;
low_pfn = cc->migrate_pfn + pageblock_nr_pages;
- high_pfn = low_pfn;
+
+ /*
+ * Take care that if the migration scanner is at the end of the zone
+ * that the free scanner does not accidentally move to the next zone
+ * in the next isolation cycle.
+ */
+ high_pfn = min(low_pfn, 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 (!suitable_migration_target(page))
continue;
- /* Found a block suitable for isolating free pages from */
- isolated = isolate_freepages_block(zone, pfn, freelist);
- nr_freepages += isolated;
+ /*
+ * Found a block suitable for isolating free pages from. Now
+ * we disabled interrupts, double check things are ok and
+ * isolate the pages. This is to minimise the time IRQs
+ * are disabled
+ */
+ isolated = 0;
+ spin_lock_irqsave(&zone->lock, flags);
+ if (suitable_migration_target(page)) {
+ isolated = isolate_freepages_block(zone, pfn, freelist);
+ nr_freepages += isolated;
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
/*
* Record the highest PFN we isolated pages from. When next
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) {
static void acct_isolated(struct zone *zone, struct compact_control *cc)
{
struct page *page;
- unsigned int count[NR_LRU_LISTS] = { 0, };
+ unsigned int count[2] = { 0, };
- list_for_each_entry(page, &cc->migratepages, lru) {
- int lru = page_lru_base_type(page);
- count[lru]++;
- }
+ list_for_each_entry(page, &cc->migratepages, lru)
+ count[!!page_is_file_cache(page)]++;
- 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);
+ __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
+ __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
}
/* Similar to reclaim, but different enough that they don't share logic */
return isolated > (inactive + active) / 2;
}
+/* possible outcome of isolate_migratepages */
+typedef enum {
+ ISOLATE_ABORT, /* Abort compaction now */
+ ISOLATE_NONE, /* No pages isolated, continue scanning */
+ ISOLATE_SUCCESS, /* Pages isolated, migrate */
+} isolate_migrate_t;
+
/*
* 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,
+static isolate_migrate_t isolate_migratepages(struct zone *zone,
struct compact_control *cc)
{
unsigned long low_pfn, end_pfn;
+ unsigned long last_pageblock_nr = 0, pageblock_nr;
unsigned long nr_scanned = 0, nr_isolated = 0;
struct list_head *migratelist = &cc->migratepages;
+ isolate_mode_t mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE;
/* Do not scan outside zone boundaries */
low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
/* 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;
+ return ISOLATE_NONE;
}
/*
* delay for some time until fewer pages are isolated
*/
while (unlikely(too_many_isolated(zone))) {
+ /* async migration should just abort */
+ if (!cc->sync)
+ return ISOLATE_ABORT;
+
congestion_wait(BLK_RW_ASYNC, HZ/10);
if (fatal_signal_pending(current))
- return 0;
+ return ISOLATE_ABORT;
}
/* Time to isolate some pages for migration */
+ cond_resched();
spin_lock_irq(&zone->lru_lock);
for (; low_pfn < end_pfn; low_pfn++) {
struct page *page;
+ bool locked = true;
+
+ /* give a chance to irqs before checking need_resched() */
+ if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) {
+ spin_unlock_irq(&zone->lru_lock);
+ locked = false;
+ }
+ if (need_resched() || spin_is_contended(&zone->lru_lock)) {
+ if (locked)
+ spin_unlock_irq(&zone->lru_lock);
+ cond_resched();
+ spin_lock_irq(&zone->lru_lock);
+ if (fatal_signal_pending(current))
+ break;
+ } else if (!locked)
+ spin_lock_irq(&zone->lru_lock);
+
if (!pfn_valid_within(low_pfn))
continue;
nr_scanned++;
if (PageBuddy(page))
continue;
+ /*
+ * For async migration, also only scan in MOVABLE blocks. Async
+ * migration is optimistic to see if the minimum amount of work
+ * satisfies the allocation
+ */
+ pageblock_nr = low_pfn >> pageblock_order;
+ if (!cc->sync && last_pageblock_nr != pageblock_nr &&
+ get_pageblock_migratetype(page) != MIGRATE_MOVABLE) {
+ low_pfn += pageblock_nr_pages;
+ low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1;
+ last_pageblock_nr = pageblock_nr;
+ continue;
+ }
+
+ if (!PageLRU(page))
+ continue;
+
+ /*
+ * PageLRU is set, and lru_lock excludes isolation,
+ * splitting and collapsing (collapsing has already
+ * happened if PageLRU is set).
+ */
+ if (PageTransHuge(page)) {
+ low_pfn += (1 << compound_order(page)) - 1;
+ continue;
+ }
+
+ if (!cc->sync)
+ mode |= ISOLATE_CLEAN;
+
/* Try isolate the page */
- if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
+ if (__isolate_lru_page(page, mode, 0) != 0)
continue;
+ VM_BUG_ON(PageTransCompound(page));
+
/* Successfully isolated */
del_page_from_lru_list(zone, page, page_lru(page));
list_add(&page->lru, migratelist);
trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
- return cc->nr_migratepages;
+ return ISOLATE_SUCCESS;
}
/*
}
static int compact_finished(struct zone *zone,
- struct compact_control *cc)
+ struct compact_control *cc)
{
unsigned int order;
- unsigned long watermark = low_wmark_pages(zone) + (1 << cc->order);
+ unsigned long watermark;
if (fatal_signal_pending(current))
return COMPACT_PARTIAL;
if (cc->free_pfn <= cc->migrate_pfn)
return COMPACT_COMPLETE;
- /* Compaction run is not finished if the watermark is not met */
- if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
+ /*
+ * order == -1 is expected when compacting via
+ * /proc/sys/vm/compact_memory
+ */
+ if (cc->order == -1)
return COMPACT_CONTINUE;
- if (cc->order == -1)
+ /* Compaction run is not finished if the watermark is not met */
+ watermark = low_wmark_pages(zone);
+ watermark += (1 << cc->order);
+
+ if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
return COMPACT_CONTINUE;
/* Direct compactor: Is a suitable page free? */
int fragindex;
unsigned long watermark;
+ /*
+ * order == -1 is expected when compacting via
+ * /proc/sys/vm/compact_memory
+ */
+ if (order == -1)
+ return COMPACT_CONTINUE;
+
/*
* Watermarks for order-0 must be met for compaction. Note the 2UL.
* This is because during migration, copies of pages need to be
* fragmentation index determines if allocation failures are due to
* low memory or external fragmentation
*
- * index of -1 implies allocations might succeed dependingon watermarks
+ * index of -1000 implies allocations might succeed depending on
+ * watermarks
* index towards 0 implies failure is due to lack of memory
* index towards 1000 implies failure is due to fragmentation
*
if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
return COMPACT_SKIPPED;
- if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0))
+ if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark,
+ 0, 0))
return COMPACT_PARTIAL;
return COMPACT_CONTINUE;
while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
unsigned long nr_migrate, nr_remaining;
+ int err;
- if (!isolate_migratepages(zone, cc))
+ switch (isolate_migratepages(zone, cc)) {
+ case ISOLATE_ABORT:
+ ret = COMPACT_PARTIAL;
+ goto out;
+ case ISOLATE_NONE:
continue;
+ case ISOLATE_SUCCESS:
+ ;
+ }
nr_migrate = cc->nr_migratepages;
- migrate_pages(&cc->migratepages, compaction_alloc,
- (unsigned long)cc, 0);
+ err = migrate_pages(&cc->migratepages, compaction_alloc,
+ (unsigned long)cc, false,
+ cc->sync);
update_nr_listpages(cc);
nr_remaining = cc->nr_migratepages;
nr_remaining);
/* Release LRU pages not migrated */
- if (!list_empty(&cc->migratepages)) {
+ if (err) {
putback_lru_pages(&cc->migratepages);
cc->nr_migratepages = 0;
}
}
+out:
/* Release free pages and check accounting */
cc->nr_freepages -= release_freepages(&cc->freepages);
VM_BUG_ON(cc->nr_freepages != 0);
return ret;
}
-unsigned long compact_zone_order(struct zone *zone,
- int order, gfp_t gfp_mask)
+static unsigned long compact_zone_order(struct zone *zone,
+ int order, gfp_t gfp_mask,
+ bool sync)
{
struct compact_control cc = {
.nr_freepages = 0,
.order = order,
.migratetype = allocflags_to_migratetype(gfp_mask),
.zone = zone,
+ .sync = sync,
};
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
* @order: The order of the current allocation
* @gfp_mask: The GFP mask of the current allocation
* @nodemask: The allowed nodes to allocate from
+ * @sync: Whether migration is synchronous or not
*
* This is the main entry point for direct page compaction.
*/
unsigned long try_to_compact_pages(struct zonelist *zonelist,
- int order, gfp_t gfp_mask, nodemask_t *nodemask)
+ int order, gfp_t gfp_mask, nodemask_t *nodemask,
+ bool sync)
{
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
int may_enter_fs = gfp_mask & __GFP_FS;
* made because an assumption is made that the page allocator can satisfy
* the "cheaper" orders without taking special steps
*/
- if (order <= PAGE_ALLOC_COSTLY_ORDER || !may_enter_fs || !may_perform_io)
+ if (!order || !may_enter_fs || !may_perform_io)
return rc;
count_vm_event(COMPACTSTALL);
nodemask) {
int status;
- status = compact_zone_order(zone, order, gfp_mask);
+ status = compact_zone_order(zone, order, gfp_mask, sync);
rc = max(status, rc);
/* If a normal allocation would succeed, stop compacting */
Code Review / linux-3.10.git / blobdiff