@@ -1703,10 +1703,18 @@ static struct page *__rmqueue(struct zone *zone, unsigned int order,
{
struct page *page;
-retry_reserve:
+retry:
page = __rmqueue_smallest(zone, order, migratetype);
if (unlikely(!page) && migratetype != MIGRATE_RESERVE) {
+
+ /*
+ * Try to get a region from the region allocator before falling
+ * back to an allocation from a different migratetype.
+ */
+ if (!del_from_region_allocator(zone, MAX_ORDER-1, migratetype))
+ goto retry;
+
page = __rmqueue_fallback(zone, order, migratetype);
/*
@@ -1716,7 +1724,7 @@ retry_reserve:
*/
if (!page) {
migratetype = MIGRATE_RESERVE;
- goto retry_reserve;
+ goto retry;
}
}
Now that we have built up an infrastructure that forms a "Memory Region Allocator", connect it with the page allocator. To entities requesting memory, the page allocator will function as a front-end, whereas the region allocator will act as a back-end to the page allocator. (Analogy: page allocator is like free cash, whereas region allocator is like a bank). Implement the flow of freepages from the region allocator to the page allocator. When __rmqueue_smallest() comes out empty handed, try to get freepages from the region allocator. If that fails, only then fallback to an allocation from a different migratetype. This helps significantly in avoiding mixing of allocations of different migratetypes in a single region. Thus it helps in keeping entire memory regions homogeneous with respect to the type of allocations. Simplification: We assume that the freepages of a memory region can be completely represented by a set of MAX_ORDER-1 pages. That is, we only need to consider the buddy freelists corresponding to MAX_ORDER-1, while interacting with the region allocator. Furthermore, we assume that pageblock_order == MAX_ORDER-1. (These assumptions are used to ease the implementation, so that one can quickly evaluate the benefits of the overall design without getting bogged down by too many corner cases and constraints. Of course future implementations will handle more scenarios and will have reduced dependence on such simplifying assumptions.) Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> --- mm/page_alloc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html