mm: add cma pcp list

Add a cma pcp list in order to increase cma memory utilization.

Increased cma memory utilization will improve overall memory
utilization because free cma pages are ignored when memory reclaim
is done with gfp mask GFP_KERNEL.

Since most memory reclaim is done by kswapd, which uses a gfp mask
of GFP_KERNEL, by increasing cma memory utilization we are therefore
ensuring that less aggressive memory reclaim takes place.

Increased cma memory utilization will improve performance,
for example it will increase app concurrency.

Change-Id: I809589a25c6abca51f1c963f118adfc78e955cf9
Signed-off-by: Liam Mark <lmark@codeaurora.org>

3 files changed, 66 insertions, 36 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index dfb8a6159997..ad4c3f186f61 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -39,8 +39,6 @@ enum {
 	MIGRATE_UNMOVABLE,
 	MIGRATE_MOVABLE,
 	MIGRATE_RECLAIMABLE,
-	MIGRATE_PCPTYPES,	/* the number of types on the pcp lists */
-	MIGRATE_HIGHATOMIC = MIGRATE_PCPTYPES,
 #ifdef CONFIG_CMA
 	/*
 	 * MIGRATE_CMA migration type is designed to mimic the way
@@ -57,6 +55,8 @@ enum {
 	 */
 	MIGRATE_CMA,
 #endif
+	MIGRATE_PCPTYPES, /* the number of types on the pcp lists */
+	MIGRATE_HIGHATOMIC = MIGRATE_PCPTYPES,
 #ifdef CONFIG_MEMORY_ISOLATION
 	MIGRATE_ISOLATE,	/* can't allocate from here */
 #endif
@@ -74,9 +74,11 @@ extern int *get_migratetype_fallbacks(int mtype);
 #ifdef CONFIG_CMA
 bool is_cma_pageblock(struct page *page);
 #  define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
+#  define get_cma_migrate_type() MIGRATE_CMA
 #else
 #  define is_cma_pageblock(page) false
 #  define is_migrate_cma(migratetype) false
+#  define get_cma_migrate_type() MIGRATE_MOVABLE
 #endif
 
 #define for_each_migratetype_order(order, type) \
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2695ca00653e..f54a84fb5e6e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1822,22 +1822,13 @@ static struct page *__rmqueue(struct zone *zone, unsigned int order,
 	return page;
 }
 
-static struct page *__rmqueue_cma(struct zone *zone, unsigned int order,
-					int migratetype, gfp_t gfp_flags)
+static struct page *__rmqueue_cma(struct zone *zone, unsigned int order)
 {
 	struct page *page = 0;
-#ifdef CONFIG_CMA
-	if (migratetype == MIGRATE_MOVABLE && !zone->cma_alloc)
-		page = __rmqueue_cma_fallback(zone, order);
-	else
-#endif
-		page = __rmqueue_smallest(zone, order, migratetype);
-
-	if (unlikely(!page)) {
-		page = __rmqueue_fallback(zone, order, migratetype);
-	}
-
-	trace_mm_page_alloc_zone_locked(page, order, migratetype);
+	if (IS_ENABLED(CONFIG_CMA))
+		if (!zone->cma_alloc)
+			page = __rmqueue_cma_fallback(zone, order);
+	trace_mm_page_alloc_zone_locked(page, order, MIGRATE_CMA);
 	return page;
 }
 
@@ -1848,15 +1839,21 @@ static struct page *__rmqueue_cma(struct zone *zone, unsigned int order,
  */
 static int rmqueue_bulk(struct zone *zone, unsigned int order,
 			unsigned long count, struct list_head *list,
-			int migratetype, bool cold, int cma)
+			int migratetype, bool cold)
 {
 	int i;
 
 	spin_lock(&zone->lock);
 	for (i = 0; i < count; ++i) {
 		struct page *page;
-		if (cma)
-			page = __rmqueue_cma(zone, order, migratetype, 0);
+
+		/*
+		 * If migrate type CMA is being requested only try to
+		 * satisfy the request with CMA pages to try and increase
+		 * CMA utlization.
+		 */
+		if (is_migrate_cma(migratetype))
+			page = __rmqueue_cma(zone, order);
 		else
 			page = __rmqueue(zone, order, migratetype, 0);
 		if (unlikely(page == NULL))
@@ -1885,6 +1882,28 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
 	return i;
 }
 
+/*
+ * Return the pcp list that corresponds to the migrate type if that list isn't
+ * empty.
+ * If the list is empty return NULL.
+ */
+static struct list_head *get_populated_pcp_list(struct zone *zone,
+			unsigned int order, struct per_cpu_pages *pcp,
+			int migratetype, int cold)
+{
+	struct list_head *list = &pcp->lists[migratetype];
+
+	if (list_empty(list)) {
+		pcp->count += rmqueue_bulk(zone, order,
+				pcp->batch, list,
+				migratetype, cold);
+
+		if (list_empty(list))
+			list = NULL;
+	}
+	return list;
+}
+
 #ifdef CONFIG_NUMA
 /*
  * Called from the vmstat counter updater to drain pagesets of this
@@ -2085,8 +2104,7 @@ void free_hot_cold_page(struct page *page, bool cold)
 	 * excessively into the page allocator
 	 */
 	if (migratetype >= MIGRATE_PCPTYPES) {
-		if (unlikely(is_migrate_isolate(migratetype)) ||
-			     is_migrate_cma(migratetype)) {
+		if (unlikely(is_migrate_isolate(migratetype))) {
 			free_one_page(zone, page, pfn, 0, migratetype);
 			goto out;
 		}
@@ -2235,22 +2253,32 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 			gfp_t gfp_flags, int alloc_flags, int migratetype)
 {
 	unsigned long flags;
-	struct page *page;
+	struct page *page = NULL;
 	bool cold = ((gfp_flags & __GFP_COLD) != 0);
 
 	if (likely(order == 0)) {
 		struct per_cpu_pages *pcp;
-		struct list_head *list;
+		struct list_head *list = NULL;
 
 		local_irq_save(flags);
 		pcp = &this_cpu_ptr(zone->pageset)->pcp;
-		list = &pcp->lists[migratetype];
-		if (list_empty(list)) {
-			pcp->count += rmqueue_bulk(zone, 0,
-					pcp->batch, list,
-					migratetype, cold,
-					gfp_flags & __GFP_CMA);
-			if (unlikely(list_empty(list)))
+
+		/* First try to get CMA pages */
+		if (migratetype == MIGRATE_MOVABLE &&
+			gfp_flags & __GFP_CMA) {
+			list = get_populated_pcp_list(zone, 0, pcp,
+					get_cma_migrate_type(), cold);
+		}
+
+		if (list == NULL) {
+			/*
+			 * Either CMA is not suitable or there are no free CMA
+			 * pages.
+			 */
+			list = get_populated_pcp_list(zone, 0, pcp,
+				migratetype, cold);
+			if (unlikely(list == NULL) ||
+				unlikely(list_empty(list)))
 				goto failed;
 		}
 
@@ -2283,13 +2311,13 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 			if (page)
 				trace_mm_page_alloc_zone_locked(page, order, migratetype);
 		}
-		if (!page) {
-		if (gfp_flags & __GFP_CMA)
-			page = __rmqueue_cma(zone, order, migratetype, gfp_flags);
-		else
+		if (!page && migratetype == MIGRATE_MOVABLE &&
+				gfp_flags & __GFP_CMA)
+			page = __rmqueue_cma(zone, order);
+
+		if (!page)
 			page = __rmqueue(zone, order, migratetype, gfp_flags);
 
-		}
 		spin_unlock(&zone->lock);
 		if (!page)
 			goto failed;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index c0e67319d3e8..ca75eeecbad1 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -927,10 +927,10 @@ static char * const migratetype_names[MIGRATE_TYPES] = {
 	"Unmovable",
 	"Movable",
 	"Reclaimable",
-	"HighAtomic",
 #ifdef CONFIG_CMA
 	"CMA",
 #endif
+	"HighAtomic",
 #ifdef CONFIG_MEMORY_ISOLATION
 	"Isolate",
 #endif