2022-08-03 03:08:17

by Abel Wu

Subject: [PATCH] mm/page_alloc: only search higher order when fallback

It seems unnecessary to search pages with order < alloc_order in
fallback allocation.

Signed-off-by: Abel Wu <[email protected]>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e008a3df0485..0abafc2fc3e0 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2934,7 +2934,7 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
* i.e. orders < pageblock_order. If there are no local zones free,
* the zonelists will be reiterated without ALLOC_NOFRAGMENT.
*/
- if (alloc_flags & ALLOC_NOFRAGMENT)
+ if (order < pageblock_order && alloc_flags & ALLOC_NOFRAGMENT)
min_order = pageblock_order;

/*
--
2.31.1

2022-08-03 08:41:59

by Vlastimil Babka

Subject: Re: [PATCH] mm/page_alloc: only search higher order when fallback

On 8/3/22 04:51, Abel Wu wrote:
> It seems unnecessary to search pages with order < alloc_order in
> fallback allocation.

This can currently happen with ALLOC_NOFRAGMENT and alloc_order >
pageblock_order, so add a test to prevent it.

> Signed-off-by: Abel Wu <[email protected]>

Acked-by: Vlastimil Babka <[email protected]>

> ---
> mm/page_alloc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index e008a3df0485..0abafc2fc3e0 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2934,7 +2934,7 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
> * i.e. orders < pageblock_order. If there are no local zones free,
> * the zonelists will be reiterated without ALLOC_NOFRAGMENT.
> */
> - if (alloc_flags & ALLOC_NOFRAGMENT)
> + if (order < pageblock_order && alloc_flags & ALLOC_NOFRAGMENT)
> min_order = pageblock_order;
>
> /*

2022-08-04 05:49:00

by Muchun Song

Subject: Re: [PATCH] mm/page_alloc: only search higher order when fallback

On Wed, Aug 3, 2022 at 10:51 AM Abel Wu <[email protected]> wrote:
>
> It seems unnecessary to search pages with order < alloc_order in
> fallback allocation.
>
> Signed-off-by: Abel Wu <[email protected]>

Reviewed-by: Muchun Song <[email protected]>

Thanks.

2022-08-04 10:17:44

by Mel Gorman

Subject: Re: [PATCH] mm/page_alloc: only search higher order when fallback

On Wed, Aug 03, 2022 at 10:51:21AM +0800, Abel Wu wrote:
> It seems unnecessary to search pages with order < alloc_order in
> fallback allocation.
>
> Signed-off-by: Abel Wu <[email protected]>

Acked-by: Mel Gorman <[email protected]>

--
Mel Gorman
SUSE Labs