diff mbox series

[RFC,v3,1/7] slub: Keep track of whether slub is on the per-node partial list

Message ID 20231024093345.3676493-2-chengming.zhou@linux.dev
State New
Headers
Series slub: Delay freezing of CPU partial slabs |

Commit Message

Chengming Zhou Oct. 24, 2023, 9:33 a.m. UTC 
  From: Chengming Zhou <zhouchengming@bytedance.com>

Now we rely on the "frozen" bit to see if we should manipulate the
slab->slab_list, which will be changed in the following patch.

Instead we introduce another way to keep track of whether slub is on
the per-node partial list, here we reuse the PG_workingset bit.

We use __set_bit and __clear_bit directly instead of the atomic version
for better performance and it's safe since it's protected by the slub
node list_lock.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
 mm/slab.h | 19 +++++++++++++++++++
 mm/slub.c |  3 +++
 2 files changed, 22 insertions(+)

Comments

Vlastimil Babka Oct. 27, 2023, 3:09 p.m. UTC | #1 
On 10/24/23 11:33, chengming.zhou@linux.dev wrote:
> From: Chengming Zhou <zhouchengming@bytedance.com>
> 
> Now we rely on the "frozen" bit to see if we should manipulate the
> slab->slab_list, which will be changed in the following patch.
> 
> Instead we introduce another way to keep track of whether slub is on
> the per-node partial list, here we reuse the PG_workingset bit.
> 
> We use __set_bit and __clear_bit directly instead of the atomic version
> for better performance and it's safe since it's protected by the slub
> node list_lock.
> 
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
> ---
>  mm/slab.h | 19 +++++++++++++++++++
>  mm/slub.c |  3 +++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/mm/slab.h b/mm/slab.h
> index 8cd3294fedf5..50522b688cfb 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h

I think these helper might just go to mm/slub.c as nothing else would use them.

> @@ -193,6 +193,25 @@ static inline void __slab_clear_pfmemalloc(struct slab *slab)
>  	__folio_clear_active(slab_folio(slab));
>  }
>  
> +/*
> + * Slub reuse PG_workingset bit to keep track of whether it's on

"SLUB reuses" ...

Looks fine otherwise!

> + * the per-node partial list.
> + */
> +static inline bool slab_test_node_partial(const struct slab *slab)
> +{
> +	return folio_test_workingset((struct folio *)slab_folio(slab));
> +}
> +
> +static inline void slab_set_node_partial(struct slab *slab)
> +{
> +	__set_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
> +}
> +
> +static inline void slab_clear_node_partial(struct slab *slab)
> +{
> +	__clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
> +}
> +
>  static inline void *slab_address(const struct slab *slab)
>  {
>  	return folio_address(slab_folio(slab));
> diff --git a/mm/slub.c b/mm/slub.c
> index 63d281dfacdb..3fad4edca34b 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2127,6 +2127,7 @@ __add_partial(struct kmem_cache_node *n, struct slab *slab, int tail)
>  		list_add_tail(&slab->slab_list, &n->partial);
>  	else
>  		list_add(&slab->slab_list, &n->partial);
> +	slab_set_node_partial(slab);
>  }
>  
>  static inline void add_partial(struct kmem_cache_node *n,
> @@ -2141,6 +2142,7 @@ static inline void remove_partial(struct kmem_cache_node *n,
>  {
>  	lockdep_assert_held(&n->list_lock);
>  	list_del(&slab->slab_list);
> +	slab_clear_node_partial(slab);
>  	n->nr_partial--;
>  }
>  
> @@ -4831,6 +4833,7 @@ static int __kmem_cache_do_shrink(struct kmem_cache *s)
>  
>  			if (free == slab->objects) {
>  				list_move(&slab->slab_list, &discard);
> +				slab_clear_node_partial(slab);
>  				n->nr_partial--;
>  				dec_slabs_node(s, node, slab->objects);
>  			} else if (free <= SHRINK_PROMOTE_MAX)
Chengming Zhou Oct. 28, 2023, 1:30 a.m. UTC | #2 
On 2023/10/27 23:09, Vlastimil Babka wrote:
> On 10/24/23 11:33, chengming.zhou@linux.dev wrote:
>> From: Chengming Zhou <zhouchengming@bytedance.com>
>>
>> Now we rely on the "frozen" bit to see if we should manipulate the
>> slab->slab_list, which will be changed in the following patch.
>>
>> Instead we introduce another way to keep track of whether slub is on
>> the per-node partial list, here we reuse the PG_workingset bit.
>>
>> We use __set_bit and __clear_bit directly instead of the atomic version
>> for better performance and it's safe since it's protected by the slub
>> node list_lock.
>>
>> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
>> ---
>>  mm/slab.h | 19 +++++++++++++++++++
>>  mm/slub.c |  3 +++
>>  2 files changed, 22 insertions(+)
>>
>> diff --git a/mm/slab.h b/mm/slab.h
>> index 8cd3294fedf5..50522b688cfb 100644
>> --- a/mm/slab.h
>> +++ b/mm/slab.h
> 
> I think these helper might just go to mm/slub.c as nothing else would use them.
> 

Ok.

>> @@ -193,6 +193,25 @@ static inline void __slab_clear_pfmemalloc(struct slab *slab)
>>  	__folio_clear_active(slab_folio(slab));
>>  }
>>  
>> +/*
>> + * Slub reuse PG_workingset bit to keep track of whether it's on
> 
> "SLUB reuses" ...
> 
> Looks fine otherwise!
> 

Will fix it. Thanks!
diff mbox series

Patch

diff --git a/mm/slab.h b/mm/slab.h
index 8cd3294fedf5..50522b688cfb 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -193,6 +193,25 @@  static inline void __slab_clear_pfmemalloc(struct slab *slab)
 	__folio_clear_active(slab_folio(slab));
 }
 
+/*
+ * Slub reuse PG_workingset bit to keep track of whether it's on
+ * the per-node partial list.
+ */
+static inline bool slab_test_node_partial(const struct slab *slab)
+{
+	return folio_test_workingset((struct folio *)slab_folio(slab));
+}
+
+static inline void slab_set_node_partial(struct slab *slab)
+{
+	__set_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
+}
+
+static inline void slab_clear_node_partial(struct slab *slab)
+{
+	__clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
+}
+
 static inline void *slab_address(const struct slab *slab)
 {
 	return folio_address(slab_folio(slab));
diff --git a/mm/slub.c b/mm/slub.c
index 63d281dfacdb..3fad4edca34b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2127,6 +2127,7 @@  __add_partial(struct kmem_cache_node *n, struct slab *slab, int tail)
 		list_add_tail(&slab->slab_list, &n->partial);
 	else
 		list_add(&slab->slab_list, &n->partial);
+	slab_set_node_partial(slab);
 }
 
 static inline void add_partial(struct kmem_cache_node *n,
@@ -2141,6 +2142,7 @@  static inline void remove_partial(struct kmem_cache_node *n,
 {
 	lockdep_assert_held(&n->list_lock);
 	list_del(&slab->slab_list);
+	slab_clear_node_partial(slab);
 	n->nr_partial--;
 }
 
@@ -4831,6 +4833,7 @@  static int __kmem_cache_do_shrink(struct kmem_cache *s)
 
 			if (free == slab->objects) {
 				list_move(&slab->slab_list, &discard);
+				slab_clear_node_partial(slab);
 				n->nr_partial--;
 				dec_slabs_node(s, node, slab->objects);
 			} else if (free <= SHRINK_PROMOTE_MAX)