When the buddy allocator releases excess free memory to the region
allocator, it does it at a region granularity - that is, it releases
all the freepages of that region to the region allocator, at once.
So, in order to make this efficient, we need a way to delete all those
pages from the buddy freelists in one shot. Add this support, and also
take care to update the nr-free statistics properly.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b66ddff..5227ac3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -853,6 +853,61 @@ page_found:
}
}
+/*
+ * Delete all freepages belonging to the region 'region_id' from 'free_list'
+ * and move them to 'list'. Using suitable list-manipulation tricks, we move
+ * the pages between the lists in one shot.
+ */
+static void del_from_freelist_bulk(struct list_head *list,
+ struct free_list *free_list, int order,
+ int region_id)
+{
+ struct mem_region_list *region, *prev_region;
+ unsigned long nr_pages = 0;
+ struct free_area *area;
+ struct list_head *cur;
+ struct page *page;
+ int prev_region_id;
+
+ region = &free_list->mr_list[region_id];
+
+ /*
+ * Perform bulk movement of all pages of the region to the new list,
+ * except the page pointed to by region->pageblock.
+ */
+ prev_region_id = find_prev_region(region_id, free_list);
+ if (prev_region_id < 0) {
+ /* This is the first region on the list */
+ list_cut_position(list, &free_list->list,
+ region->page_block->prev);
+ } else {
+ prev_region = &free_list->mr_list[prev_region_id];
+ list_cut_position(list, prev_region->page_block,
+ region->page_block->prev);
+ }
+
+ list_for_each(cur, list)
+ nr_pages++;
+
+ region->nr_free -= nr_pages;
+
+ /*
+ * Now delete the page pointed to by region->page_block using
+ * del_from_freelist(), so that it sets up the region related
+ * data-structures of the freelist properly.
+ */
+ page = list_entry(region->page_block, struct page, lru);
+ del_from_freelist(page, free_list, order);
+
+ list_add_tail(&page->lru, list);
+
+ area = &(page_zone(page)->free_area[order]);
+ area->nr_free -= nr_pages + 1;
+
+ /* Fix up the zone region stats, since del_from_freelist() altered it */
+ region->zone_region->nr_free += 1 << order;
+}
+
/**
* Move a given page from one freelist to another.
*/
--
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