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-rw-r--r--mm/compaction.c90
1 files changed, 79 insertions, 11 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 7168edc..0fbc6b7 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -91,6 +91,60 @@ static inline bool compact_trylock_irqsave(spinlock_t *lock,
return compact_checklock_irqsave(lock, flags, false, cc);
}
+static void compact_capture_page(struct compact_control *cc)
+{
+ unsigned long flags;
+ int mtype, mtype_low, mtype_high;
+
+ if (!cc->page || *cc->page)
+ return;
+
+ /*
+ * For MIGRATE_MOVABLE allocations we capture a suitable page ASAP
+ * regardless of the migratetype of the freelist is is captured from.
+ * This is fine because the order for a high-order MIGRATE_MOVABLE
+ * allocation is typically at least a pageblock size and overall
+ * fragmentation is not impaired. Other allocation types must
+ * capture pages from their own migratelist because otherwise they
+ * could pollute other pageblocks like MIGRATE_MOVABLE with
+ * difficult to move pages and making fragmentation worse overall.
+ */
+ if (cc->migratetype == MIGRATE_MOVABLE) {
+ mtype_low = 0;
+ mtype_high = MIGRATE_PCPTYPES;
+ } else {
+ mtype_low = cc->migratetype;
+ mtype_high = cc->migratetype + 1;
+ }
+
+ /* Speculatively examine the free lists without zone lock */
+ for (mtype = mtype_low; mtype < mtype_high; mtype++) {
+ int order;
+ for (order = cc->order; order < MAX_ORDER; order++) {
+ struct page *page;
+ struct free_area *area;
+ area = &(cc->zone->free_area[order]);
+ if (list_empty(&area->free_list[mtype]))
+ continue;
+
+ /* Take the lock and attempt capture of the page */
+ if (!compact_trylock_irqsave(&cc->zone->lock, &flags, cc))
+ return;
+ if (!list_empty(&area->free_list[mtype])) {
+ page = list_entry(area->free_list[mtype].next,
+ struct page, lru);
+ if (capture_free_page(page, cc->order, mtype)) {
+ spin_unlock_irqrestore(&cc->zone->lock,
+ flags);
+ *cc->page = page;
+ return;
+ }
+ }
+ spin_unlock_irqrestore(&cc->zone->lock, flags);
+ }
+ }
+}
+
/*
* Isolate free pages onto a private freelist. Caller must hold zone->lock.
* If @strict is true, will abort returning 0 on any invalid PFNs or non-free
@@ -645,7 +699,6 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
static int compact_finished(struct zone *zone,
struct compact_control *cc)
{
- unsigned int order;
unsigned long watermark;
if (fatal_signal_pending(current))
@@ -688,14 +741,22 @@ static int compact_finished(struct zone *zone,
return COMPACT_CONTINUE;
/* Direct compactor: Is a suitable page free? */
- for (order = cc->order; order < MAX_ORDER; order++) {
- /* Job done if page is free of the right migratetype */
- if (!list_empty(&zone->free_area[order].free_list[cc->migratetype]))
- return COMPACT_PARTIAL;
-
- /* Job done if allocation would set block type */
- if (order >= pageblock_order && zone->free_area[order].nr_free)
+ if (cc->page) {
+ /* Was a suitable page captured? */
+ if (*cc->page)
return COMPACT_PARTIAL;
+ } else {
+ unsigned int order;
+ for (order = cc->order; order < MAX_ORDER; order++) {
+ struct free_area *area = &zone->free_area[cc->order];
+ /* Job done if page is free of the right migratetype */
+ if (!list_empty(&area->free_list[cc->migratetype]))
+ return COMPACT_PARTIAL;
+
+ /* Job done if allocation would set block type */
+ if (cc->order >= pageblock_order && area->nr_free)
+ return COMPACT_PARTIAL;
+ }
}
return COMPACT_CONTINUE;
@@ -817,6 +878,9 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
goto out;
}
}
+
+ /* Capture a page now if it is a suitable size */
+ compact_capture_page(cc);
}
out:
@@ -829,7 +893,8 @@ out:
static unsigned long compact_zone_order(struct zone *zone,
int order, gfp_t gfp_mask,
- bool sync, bool *contended)
+ bool sync, bool *contended,
+ struct page **page)
{
struct compact_control cc = {
.nr_freepages = 0,
@@ -839,6 +904,7 @@ static unsigned long compact_zone_order(struct zone *zone,
.zone = zone,
.sync = sync,
.contended = contended,
+ .page = page,
};
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
@@ -860,7 +926,7 @@ int sysctl_extfrag_threshold = 500;
*/
unsigned long try_to_compact_pages(struct zonelist *zonelist,
int order, gfp_t gfp_mask, nodemask_t *nodemask,
- bool sync, bool *contended)
+ bool sync, bool *contended, struct page **page)
{
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
int may_enter_fs = gfp_mask & __GFP_FS;
@@ -881,7 +947,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
int status;
status = compact_zone_order(zone, order, gfp_mask, sync,
- contended);
+ contended, page);
rc = max(status, rc);
/* If a normal allocation would succeed, stop compacting */
@@ -936,6 +1002,7 @@ int compact_pgdat(pg_data_t *pgdat, int order)
struct compact_control cc = {
.order = order,
.sync = false,
+ .page = NULL,
};
return __compact_pgdat(pgdat, &cc);
@@ -946,6 +1013,7 @@ static int compact_node(int nid)
struct compact_control cc = {
.order = -1,
.sync = true,
+ .page = NULL,
};
return __compact_pgdat(NODE_DATA(nid), &cc);
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