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SubjectRe: [PATCH] fix page_alloc for larger I/O segments
On Thu, 13 Dec 2007 19:40:09 -0500
Mark Lord <liml@rtr.ca> wrote:

> And here is a patch that seems to fix it for me here:
>
> * * * *
>
> Fix page allocator to give better change of larger contiguous segments (again).
>
> Signed-off-by: Mark Lord <mlord@pobox.com
> ---
>
>
> --- old/mm/page_alloc.c.orig 2007-12-13 19:25:15.000000000 -0500
> +++ linux-2.6/mm/page_alloc.c 2007-12-13 19:35:50.000000000 -0500
> @@ -954,7 +954,7 @@
> goto failed;
> }
> /* Find a page of the appropriate migrate type */
> - list_for_each_entry(page, &pcp->list, lru) {
> + list_for_each_entry_reverse(page, &pcp->list, lru) {
> if (page_private(page) == migratetype) {
> list_del(&page->lru);
> pcp->count--;

- needs help to make it apply to mainline

- needs a comment, methinks...


--- a/mm/page_alloc.c~fix-page-allocator-to-give-better-chance-of-larger-contiguous-segments-again
+++ a/mm/page_alloc.c
@@ -1060,8 +1060,12 @@ again:
goto failed;
}

- /* Find a page of the appropriate migrate type */
- list_for_each_entry(page, &pcp->list, lru)
+ /*
+ * Find a page of the appropriate migrate type. Doing a
+ * reverse-order search here helps us to hand out pages in
+ * ascending physical-address order.
+ */
+ list_for_each_entry_reverse(page, &pcp->list, lru)
if (page_private(page) == migratetype)
break;

_


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