diff mbox series

[RFC,v3,2/7] slub: Prepare __slab_free() for unfrozen partial slab out of node partial list

Message ID 20231024093345.3676493-3-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 the partial slub will be frozen when taken out of node partial list,
so the __slab_free() will know from "was_frozen" that the partial slab
is not on node partial list and is used by one kmem_cache_cpu.

But we will change this, make partial slabs leave the node partial list
with unfrozen state, so we need to change __slab_free() to use the new
slab_test_node_partial() we just introduced.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
 mm/slub.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Vlastimil Babka Oct. 27, 2023, 3:18 p.m. UTC | #1 
On 10/24/23 11:33, chengming.zhou@linux.dev wrote:
> From: Chengming Zhou <zhouchengming@bytedance.com>
> 
> Now the partial slub will be frozen when taken out of node partial list,

	  partially empty slab

> so the __slab_free() will know from "was_frozen" that the partial slab
> is not on node partial list and is used by one kmem_cache_cpu.

				... is a cpu or cpu partial slab of some cpu.

> But we will change this, make partial slabs leave the node partial list
> with unfrozen state, so we need to change __slab_free() to use the new
> slab_test_node_partial() we just introduced.
> 
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
> ---
>  mm/slub.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 3fad4edca34b..f568a32d7332 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -3610,6 +3610,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>  	unsigned long counters;
>  	struct kmem_cache_node *n = NULL;
>  	unsigned long flags;
> +	bool on_node_partial;
>  
>  	stat(s, FREE_SLOWPATH);
>  
> @@ -3657,6 +3658,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>  				 */
>  				spin_lock_irqsave(&n->list_lock, flags);
>  
> +				on_node_partial = slab_test_node_partial(slab);
>  			}
>  		}
>  
> @@ -3685,6 +3687,15 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>  		return;
>  	}
>  
> +	/*
> +	 * This slab was partial but not on the per-node partial list,

This slab was partially empty ...

Otherwise LGTM!

> +	 * in which case we shouldn't manipulate its list, just return.
> +	 */
> +	if (prior && !on_node_partial) {
> +		spin_unlock_irqrestore(&n->list_lock, flags);
> +		return;
> +	}
> +
>  	if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
>  		goto slab_empty;
>
Chengming Zhou Oct. 28, 2023, 1:35 a.m. UTC | #2 
On 2023/10/27 23:18, Vlastimil Babka wrote:
> On 10/24/23 11:33, chengming.zhou@linux.dev wrote:
>> From: Chengming Zhou <zhouchengming@bytedance.com>
>>
>> Now the partial slub will be frozen when taken out of node partial list,
> 
> 	  partially empty slab
> 
>> so the __slab_free() will know from "was_frozen" that the partial slab
>> is not on node partial list and is used by one kmem_cache_cpu.
> 
> 				... is a cpu or cpu partial slab of some cpu.
> 
>> But we will change this, make partial slabs leave the node partial list
>> with unfrozen state, so we need to change __slab_free() to use the new
>> slab_test_node_partial() we just introduced.
>>
>> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
>> ---
>>  mm/slub.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/mm/slub.c b/mm/slub.c
>> index 3fad4edca34b..f568a32d7332 100644
>> --- a/mm/slub.c
>> +++ b/mm/slub.c
>> @@ -3610,6 +3610,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>>  	unsigned long counters;
>>  	struct kmem_cache_node *n = NULL;
>>  	unsigned long flags;
>> +	bool on_node_partial;
>>  
>>  	stat(s, FREE_SLOWPATH);
>>  
>> @@ -3657,6 +3658,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>>  				 */
>>  				spin_lock_irqsave(&n->list_lock, flags);
>>  
>> +				on_node_partial = slab_test_node_partial(slab);
>>  			}
>>  		}
>>  
>> @@ -3685,6 +3687,15 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>>  		return;
>>  	}
>>  
>> +	/*
>> +	 * This slab was partial but not on the per-node partial list,
> 
> This slab was partially empty ...
> 
> Otherwise LGTM!

Ok, will fix.

Thanks!

> 
>> +	 * in which case we shouldn't manipulate its list, just return.
>> +	 */
>> +	if (prior && !on_node_partial) {
>> +		spin_unlock_irqrestore(&n->list_lock, flags);
>> +		return;
>> +	}
>> +
>>  	if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
>>  		goto slab_empty;
>>  
>
diff mbox series

Patch

diff --git a/mm/slub.c b/mm/slub.c
index 3fad4edca34b..f568a32d7332 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3610,6 +3610,7 @@  static void __slab_free(struct kmem_cache *s, struct slab *slab,
 	unsigned long counters;
 	struct kmem_cache_node *n = NULL;
 	unsigned long flags;
+	bool on_node_partial;
 
 	stat(s, FREE_SLOWPATH);
 
@@ -3657,6 +3658,7 @@  static void __slab_free(struct kmem_cache *s, struct slab *slab,
 				 */
 				spin_lock_irqsave(&n->list_lock, flags);
 
+				on_node_partial = slab_test_node_partial(slab);
 			}
 		}
 
@@ -3685,6 +3687,15 @@  static void __slab_free(struct kmem_cache *s, struct slab *slab,
 		return;
 	}
 
+	/*
+	 * This slab was partial but not on the per-node partial list,
+	 * in which case we shouldn't manipulate its list, just return.
+	 */
+	if (prior && !on_node_partial) {
+		spin_unlock_irqrestore(&n->list_lock, flags);
+		return;
+	}
+
 	if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
 		goto slab_empty;