Re: [PATCH 2/5] mm/page_alloc: Add a bulk page allocator

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Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> writes:


diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 8572a1474e16..4903d1cc48dc 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -515,6 +515,10 @@ static inline int arch_make_page_accessible(struct page *page)
 }
 #endif
+int __alloc_pages_bulk_nodemask(gfp_t gfp_mask, int preferred_nid, + nodemask_t *nodemask, int nr_pages,
+				struct list_head *list);
+
 struct page *
__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid, nodemask_t *nodemask); @@ -525,6 +529,14 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order, int preferred_nid) return __alloc_pages_nodemask(gfp_mask, order, preferred_nid, NULL);
 }
+/* Bulk allocate order-0 pages */
+static inline unsigned long
+alloc_pages_bulk(gfp_t gfp_mask, unsigned long nr_pages, struct list_head *list)
+{
+ return __alloc_pages_bulk_nodemask(gfp_mask, numa_mem_id(), NULL, + nr_pages, list);

Is the second line indentation intentional ? Why not align it to the first argument (gfp_mask) ?

+}
+
 /*
* Allocate pages, preferring the node given as nid. The node must be valid and
  * online. For more general interface, see alloc_pages_node().
@@ -594,6 +606,7 @@ void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask); extern void __free_pages(struct page *page, unsigned int order);
 extern void free_pages(unsigned long addr, unsigned int order);
+extern void free_pages_bulk(struct list_head *list);
struct page_frag_cache; extern void __page_frag_cache_drain(struct page *page, unsigned int count);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3e4b29ee2b1e..ff1e55793786 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4436,6 +4436,21 @@ static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
 	}
 }
...
+/* + * This is a batched version of the page allocator that attempts to + * allocate nr_pages quickly from the preferred zone and add them to list.
+ */
+int __alloc_pages_bulk_nodemask(gfp_t gfp_mask, int preferred_nid,
+			nodemask_t *nodemask, int nr_pages,
+			struct list_head *alloc_list)
+{
+	struct page *page;
+	unsigned long flags;
+	struct zone *zone;
+	struct zoneref *z;
+	struct per_cpu_pages *pcp;
+	struct list_head *pcp_list;
+	struct alloc_context ac;
+	gfp_t alloc_mask;
+	unsigned int alloc_flags;
+	int alloced = 0;

Does alloced count the number of allocated pages ? Do you mind renaming it to 'allocated' ?

+
+	if (nr_pages == 1)
+		goto failed;
+
+ /* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */ + if (!prepare_alloc_pages(gfp_mask, 0, preferred_nid, nodemask, &ac, &alloc_mask, &alloc_flags))
+		return 0;
+	gfp_mask = alloc_mask;
+
+ /* Find an allowed local zone that meets the high watermark. */ + for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zoneidx, ac.nodemask) {
+		unsigned long mark;
+
+ if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) &&
+		    !__cpuset_zone_allowed(zone, gfp_mask)) {
+			continue;
+		}
+
+ if (nr_online_nodes > 1 && zone != ac.preferred_zoneref->zone && + zone_to_nid(zone) != zone_to_nid(ac.preferred_zoneref->zone)) {
+			goto failed;
+		}
+
+ mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages;
+		if (zone_watermark_fast(zone, 0,  mark,
+ zonelist_zone_idx(ac.preferred_zoneref),
+				alloc_flags, gfp_mask)) {
+			break;
+		}
+	}
+	if (!zone)
+		return 0;
+
+	/* Attempt the batch allocation */
+	local_irq_save(flags);
+	pcp = &this_cpu_ptr(zone->pageset)->pcp;
+	pcp_list = &pcp->lists[ac.migratetype];
+
+	while (alloced < nr_pages) {
+ page = __rmqueue_pcplist(zone, ac.migratetype, alloc_flags, + pcp, pcp_list);

Same indentation comment as before

+		if (!page)
+			break;
+
+		prep_new_page(page, 0, gfp_mask, 0);
+		list_add(&page->lru, alloc_list);
+		alloced++;
+	}
+
+	if (!alloced)
+		goto failed_irq;
+
+	if (alloced) {
+ __count_zid_vm_events(PGALLOC, zone_idx(zone), alloced);
+		zone_statistics(zone, zone);
+	}
+
+	local_irq_restore(flags);
+
+	return alloced;
+
+failed_irq:
+	local_irq_restore(flags);
+
+failed:
+ page = __alloc_pages_nodemask(gfp_mask, 0, preferred_nid, nodemask);
+	if (page) {
+		alloced++;
+		list_add(&page->lru, alloc_list);
+	}
+
+	return alloced;
+}
+EXPORT_SYMBOL_GPL(__alloc_pages_bulk_nodemask);
+
 /*
  * This is the 'heart' of the zoned buddy allocator.
  */
@@ -4981,8 +5092,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 		return NULL;
 	}
- gfp_mask &= gfp_allowed_mask;
-	alloc_mask = gfp_mask;
if (!prepare_alloc_pages(gfp_mask, order, preferred_nid, nodemask, &ac, &alloc_mask, &alloc_flags))
 		return NULL;





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