* [PATCH] mm/memcg: remove unneeded nr_scanned
@ 2022-03-28 11:41 Miaohe Lin
2022-03-28 12:01 ` Michal Hocko
` (3 more replies)
0 siblings, 4 replies; 6+ messages in thread
From: Miaohe Lin @ 2022-03-28 11:41 UTC (permalink / raw)
To: hannes, mhocko, roman.gushchin, shakeelb, akpm
Cc: cgroups, linux-mm, linux-kernel, linmiaohe
The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim always
does *total_scanned += nr_scanned. So we can pass total_scanned directly to
the mem_cgroup_soft_reclaim to simplify the code and save some cpu cycles
of adding nr_scanned to total_scanned.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/memcontrol.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b686ec4f42c6..79341365ec90 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3384,7 +3384,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
int loop = 0;
struct mem_cgroup_tree_per_node *mctz;
unsigned long excess;
- unsigned long nr_scanned;
if (order > 0)
return 0;
@@ -3412,11 +3411,9 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
if (!mz)
break;
- nr_scanned = 0;
reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
- gfp_mask, &nr_scanned);
+ gfp_mask, total_scanned);
nr_reclaimed += reclaimed;
- *total_scanned += nr_scanned;
spin_lock_irq(&mctz->lock);
__mem_cgroup_remove_exceeded(mz, mctz);
--
2.23.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] mm/memcg: remove unneeded nr_scanned
2022-03-28 11:41 [PATCH] mm/memcg: remove unneeded nr_scanned Miaohe Lin
@ 2022-03-28 12:01 ` Michal Hocko
2022-03-28 13:15 ` Miaohe Lin
2022-03-28 14:16 ` David Hildenbrand
` (2 subsequent siblings)
3 siblings, 1 reply; 6+ messages in thread
From: Michal Hocko @ 2022-03-28 12:01 UTC (permalink / raw)
To: Miaohe Lin
Cc: hannes, roman.gushchin, shakeelb, akpm, cgroups, linux-mm, linux-kernel
On Mon 28-03-22 19:41:44, Miaohe Lin wrote:
> The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim always
> does *total_scanned += nr_scanned. So we can pass total_scanned directly to
> the mem_cgroup_soft_reclaim to simplify the code and save some cpu cycles
> of adding nr_scanned to total_scanned.
Maybe the compiler could be clever enough to generate a good code.
mem_cgroup_soft_reclaim doesn't have other caller so it could be
inlined. But I do agree that the change makes sense because it makes the
code more consistent as mem_cgroup_soft_limit_reclaim already uses
total_scanned this way.
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Thanks
> ---
> mm/memcontrol.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b686ec4f42c6..79341365ec90 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3384,7 +3384,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
> int loop = 0;
> struct mem_cgroup_tree_per_node *mctz;
> unsigned long excess;
> - unsigned long nr_scanned;
>
> if (order > 0)
> return 0;
> @@ -3412,11 +3411,9 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
> if (!mz)
> break;
>
> - nr_scanned = 0;
> reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
> - gfp_mask, &nr_scanned);
> + gfp_mask, total_scanned);
> nr_reclaimed += reclaimed;
> - *total_scanned += nr_scanned;
> spin_lock_irq(&mctz->lock);
> __mem_cgroup_remove_exceeded(mz, mctz);
>
> --
> 2.23.0
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mm/memcg: remove unneeded nr_scanned
2022-03-28 12:01 ` Michal Hocko
@ 2022-03-28 13:15 ` Miaohe Lin
0 siblings, 0 replies; 6+ messages in thread
From: Miaohe Lin @ 2022-03-28 13:15 UTC (permalink / raw)
To: Michal Hocko
Cc: hannes, roman.gushchin, shakeelb, akpm, cgroups, linux-mm, linux-kernel
On 2022/3/28 20:01, Michal Hocko wrote:
> On Mon 28-03-22 19:41:44, Miaohe Lin wrote:
>> The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim always
>> does *total_scanned += nr_scanned. So we can pass total_scanned directly to
>> the mem_cgroup_soft_reclaim to simplify the code and save some cpu cycles
>> of adding nr_scanned to total_scanned.
>
> Maybe the compiler could be clever enough to generate a good code.
> mem_cgroup_soft_reclaim doesn't have other caller so it could be
> inlined. But I do agree that the change makes sense because it makes the
> code more consistent as mem_cgroup_soft_limit_reclaim already uses
> total_scanned this way.
Many thanks for your comment and Acked-by tag. :)
>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>
> Acked-by: Michal Hocko <mhocko@suse.com>
>
> Thanks
>
>> ---
>> mm/memcontrol.c | 5 +----
>> 1 file changed, 1 insertion(+), 4 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index b686ec4f42c6..79341365ec90 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -3384,7 +3384,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
>> int loop = 0;
>> struct mem_cgroup_tree_per_node *mctz;
>> unsigned long excess;
>> - unsigned long nr_scanned;
>>
>> if (order > 0)
>> return 0;
>> @@ -3412,11 +3411,9 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
>> if (!mz)
>> break;
>>
>> - nr_scanned = 0;
>> reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
>> - gfp_mask, &nr_scanned);
>> + gfp_mask, total_scanned);
>> nr_reclaimed += reclaimed;
>> - *total_scanned += nr_scanned;
>> spin_lock_irq(&mctz->lock);
>> __mem_cgroup_remove_exceeded(mz, mctz);
>>
>> --
>> 2.23.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mm/memcg: remove unneeded nr_scanned
2022-03-28 11:41 [PATCH] mm/memcg: remove unneeded nr_scanned Miaohe Lin
2022-03-28 12:01 ` Michal Hocko
@ 2022-03-28 14:16 ` David Hildenbrand
2022-03-28 18:36 ` Roman Gushchin
2022-04-01 1:06 ` Wei Yang
3 siblings, 0 replies; 6+ messages in thread
From: David Hildenbrand @ 2022-03-28 14:16 UTC (permalink / raw)
To: Miaohe Lin, hannes, mhocko, roman.gushchin, shakeelb, akpm
Cc: cgroups, linux-mm, linux-kernel
On 28.03.22 13:41, Miaohe Lin wrote:
> The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim always
> does *total_scanned += nr_scanned. So we can pass total_scanned directly to
> the mem_cgroup_soft_reclaim to simplify the code and save some cpu cycles
> of adding nr_scanned to total_scanned.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> mm/memcontrol.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b686ec4f42c6..79341365ec90 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3384,7 +3384,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
> int loop = 0;
> struct mem_cgroup_tree_per_node *mctz;
> unsigned long excess;
> - unsigned long nr_scanned;
>
> if (order > 0)
> return 0;
> @@ -3412,11 +3411,9 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
> if (!mz)
> break;
>
> - nr_scanned = 0;
> reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
> - gfp_mask, &nr_scanned);
> + gfp_mask, total_scanned);
> nr_reclaimed += reclaimed;
> - *total_scanned += nr_scanned;
> spin_lock_irq(&mctz->lock);
> __mem_cgroup_remove_exceeded(mz, mctz);
>
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mm/memcg: remove unneeded nr_scanned
2022-03-28 11:41 [PATCH] mm/memcg: remove unneeded nr_scanned Miaohe Lin
2022-03-28 12:01 ` Michal Hocko
2022-03-28 14:16 ` David Hildenbrand
@ 2022-03-28 18:36 ` Roman Gushchin
2022-04-01 1:06 ` Wei Yang
3 siblings, 0 replies; 6+ messages in thread
From: Roman Gushchin @ 2022-03-28 18:36 UTC (permalink / raw)
To: Miaohe Lin
Cc: hannes, mhocko, shakeelb, akpm, cgroups, linux-mm, linux-kernel
On Mon, Mar 28, 2022 at 07:41:44PM +0800, Miaohe Lin wrote:
> The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim always
> does *total_scanned += nr_scanned. So we can pass total_scanned directly to
> the mem_cgroup_soft_reclaim to simplify the code and save some cpu cycles
> of adding nr_scanned to total_scanned.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Thanks!
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mm/memcg: remove unneeded nr_scanned
2022-03-28 11:41 [PATCH] mm/memcg: remove unneeded nr_scanned Miaohe Lin
` (2 preceding siblings ...)
2022-03-28 18:36 ` Roman Gushchin
@ 2022-04-01 1:06 ` Wei Yang
3 siblings, 0 replies; 6+ messages in thread
From: Wei Yang @ 2022-04-01 1:06 UTC (permalink / raw)
To: Miaohe Lin
Cc: hannes, mhocko, roman.gushchin, shakeelb, akpm, cgroups,
linux-mm, linux-kernel
On Mon, Mar 28, 2022 at 07:41:44PM +0800, Miaohe Lin wrote:
>The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim always
>does *total_scanned += nr_scanned. So we can pass total_scanned directly to
>the mem_cgroup_soft_reclaim to simplify the code and save some cpu cycles
>of adding nr_scanned to total_scanned.
>
>Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>---
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Thanks
--
Wei Yang
Help you, Help me
^ permalink raw reply [flat|nested] 6+ messages in thread
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2022-03-28 11:41 [PATCH] mm/memcg: remove unneeded nr_scanned Miaohe Lin
2022-03-28 12:01 ` Michal Hocko
2022-03-28 13:15 ` Miaohe Lin
2022-03-28 14:16 ` David Hildenbrand
2022-03-28 18:36 ` Roman Gushchin
2022-04-01 1:06 ` Wei Yang
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