2023-02-03 10:10:17

by Yajun Deng

Subject: [PATCH] mm/page_alloc: reduce fallbacks to (MIGRATE_PCPTYPES - 1)

The commit 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable
pageblocks with others") has removed MIGRATE_CMA and MIGRATE_ISOLATE from
fallbacks list. so there is no need to add an element at the end of every
type.

Reduce fallbacks to (MIGRATE_PCPTYPES - 1).

Signed-off-by: Yajun Deng <[email protected]>
---
mm/page_alloc.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5ebce58026f1..21d820c42900 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2603,10 +2603,10 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
*
* The other migratetypes do not have fallbacks.
*/
-static int fallbacks[MIGRATE_TYPES][3] = {
- [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
- [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
- [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
+static int fallbacks[MIGRATE_TYPES][MIGRATE_PCPTYPES - 1] = {
+ [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE },
+ [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
+ [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },
};

#ifdef CONFIG_CMA
@@ -2865,11 +2865,8 @@ int find_suitable_fallback(struct free_area *area, unsigned int order,
return -1;

*can_steal = false;
- for (i = 0;; i++) {
+ for (i = 0; i < MIGRATE_PCPTYPES - 1 ; i++) {
fallback_mt = fallbacks[migratetype][i];
- if (fallback_mt == MIGRATE_TYPES)
- break;
-
if (free_area_empty(area, fallback_mt))
continue;

--
2.25.1

2023-02-08 16:07:19

by Vlastimil Babka

Subject: Re: [PATCH] mm/page_alloc: reduce fallbacks to (MIGRATE_PCPTYPES - 1)

On 2/3/23 23:23, Andrew Morton wrote:
> On Fri, 3 Feb 2023 18:01:32 +0800 Yajun Deng <[email protected]> wrote:
>
>> The commit 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable
>> pageblocks with others") has removed MIGRATE_CMA and MIGRATE_ISOLATE from
>> fallbacks list. so there is no need to add an element at the end of every
>> type.
>>
>> Reduce fallbacks to (MIGRATE_PCPTYPES - 1).


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

> Thanks. `git log' suggests who should be cc'ed when fixing things...
>
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -2603,10 +2603,10 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
>> *
>> * The other migratetypes do not have fallbacks.
>> */
>> -static int fallbacks[MIGRATE_TYPES][3] = {
>> - [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
>> - [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
>> - [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
>> +static int fallbacks[MIGRATE_TYPES][MIGRATE_PCPTYPES - 1] = {

Why not also reduce the first index size from [MIGRATE_TYPES] to
[MIGRATE_PCPTYPES] ?

>> + [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE },
>> + [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
>> + [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },
>> };
>>
>> #ifdef CONFIG_CMA
>> @@ -2865,11 +2865,8 @@ int find_suitable_fallback(struct free_area *area, unsigned int order,
>> return -1;
>>
>> *can_steal = false;
>> - for (i = 0;; i++) {
>> + for (i = 0; i < MIGRATE_PCPTYPES - 1 ; i++) {
>> fallback_mt = fallbacks[migratetype][i];
>> - if (fallback_mt == MIGRATE_TYPES)
>> - break;
>> -
>> if (free_area_empty(area, fallback_mt))
>> continue;
>>
>> --
>> 2.25.1

2023-02-09 02:03:04

by Yajun Deng

Subject: Re: [PATCH] mm/page_alloc: reduce fallbacks to (MIGRATE_PCPTYPES - 1)

February 9, 2023 12:07 AM, "Vlastimil Babka" <[email protected]> wrote:

> On 2/3/23 23:23, Andrew Morton wrote:
>
>> On Fri, 3 Feb 2023 18:01:32 +0800 Yajun Deng <[email protected]> wrote:
>>
>>> The commit 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable
>>> pageblocks with others") has removed MIGRATE_CMA and MIGRATE_ISOLATE from
>>> fallbacks list. so there is no need to add an element at the end of every
>>> type.
>>>
>>> Reduce fallbacks to (MIGRATE_PCPTYPES - 1).
>
> Acked-by: Vlastimil Babka <[email protected]>
>
>> Thanks. `git log' suggests who should be cc'ed when fixing things...
>>
>>> --- a/mm/page_alloc.c
>>> +++ b/mm/page_alloc.c
>>> @@ -2603,10 +2603,10 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
>>> *
>>> * The other migratetypes do not have fallbacks.
>>> */
>>> -static int fallbacks[MIGRATE_TYPES][3] = {
>>> - [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
>>> - [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
>>> - [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
>>> +static int fallbacks[MIGRATE_TYPES][MIGRATE_PCPTYPES - 1] = {
>
> Why not also reduce the first index size from [MIGRATE_TYPES] to
> [MIGRATE_PCPTYPES] ?
>

I overlooked this. I'll do it in the next patch.

>>> + [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE },
>>> + [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
>>> + [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },
>>> };
>>>
>>> #ifdef CONFIG_CMA
>>> @@ -2865,11 +2865,8 @@ int find_suitable_fallback(struct free_area *area, unsigned int order,
>>> return -1;
>>>
>>> *can_steal = false;
>>> - for (i = 0;; i++) {
>>> + for (i = 0; i < MIGRATE_PCPTYPES - 1 ; i++) {
>>> fallback_mt = fallbacks[migratetype][i];
>>> - if (fallback_mt == MIGRATE_TYPES)
>>> - break;
>>> -
>>> if (free_area_empty(area, fallback_mt))
>>> continue;
>>>
>>> --
>>> 2.25.1