diff mbox series

[v2,28/47] bcache: dynamically allocate the md-bcache shrinker

Message ID 20230724094354.90817-29-zhengqi.arch@bytedance.com (mailing list archive)
State Superseded, archived
Headers show
Series use refcount+RCU method to implement lockless slab shrink | expand

Commit Message

Qi Zheng July 24, 2023, 9:43 a.m. UTC
In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the md-bcache shrinker, so that it can be freed
asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
read-side critical section when releasing the struct cache_set.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 drivers/md/bcache/bcache.h |  2 +-
 drivers/md/bcache/btree.c  | 27 ++++++++++++++++-----------
 drivers/md/bcache/sysfs.c  |  3 ++-
 3 files changed, 19 insertions(+), 13 deletions(-)

Comments

Muchun Song July 26, 2023, 7:32 a.m. UTC | #1
On 2023/7/24 17:43, Qi Zheng wrote:
> In preparation for implementing lockless slab shrink, use new APIs to
> dynamically allocate the md-bcache shrinker, so that it can be freed
> asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
> read-side critical section when releasing the struct cache_set.
>
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> ---
>   drivers/md/bcache/bcache.h |  2 +-
>   drivers/md/bcache/btree.c  | 27 ++++++++++++++++-----------
>   drivers/md/bcache/sysfs.c  |  3 ++-
>   3 files changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> index 5a79bb3c272f..c622bc50f81b 100644
> --- a/drivers/md/bcache/bcache.h
> +++ b/drivers/md/bcache/bcache.h
> @@ -541,7 +541,7 @@ struct cache_set {
>   	struct bio_set		bio_split;
>   
>   	/* For the btree cache */
> -	struct shrinker		shrink;
> +	struct shrinker		*shrink;
>   
>   	/* For the btree cache and anything allocation related */
>   	struct mutex		bucket_lock;
> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> index fd121a61f17c..c176c7fc77d9 100644
> --- a/drivers/md/bcache/btree.c
> +++ b/drivers/md/bcache/btree.c
> @@ -667,7 +667,7 @@ static int mca_reap(struct btree *b, unsigned int min_order, bool flush)
>   static unsigned long bch_mca_scan(struct shrinker *shrink,
>   				  struct shrink_control *sc)
>   {
> -	struct cache_set *c = container_of(shrink, struct cache_set, shrink);
> +	struct cache_set *c = shrink->private_data;
>   	struct btree *b, *t;
>   	unsigned long i, nr = sc->nr_to_scan;
>   	unsigned long freed = 0;
> @@ -734,7 +734,7 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
>   static unsigned long bch_mca_count(struct shrinker *shrink,
>   				   struct shrink_control *sc)
>   {
> -	struct cache_set *c = container_of(shrink, struct cache_set, shrink);
> +	struct cache_set *c = shrink->private_data;
>   
>   	if (c->shrinker_disabled)
>   		return 0;
> @@ -752,8 +752,8 @@ void bch_btree_cache_free(struct cache_set *c)
>   
>   	closure_init_stack(&cl);
>   
> -	if (c->shrink.list.next)
> -		unregister_shrinker(&c->shrink);
> +	if (c->shrink)
> +		shrinker_unregister(c->shrink);
>   
>   	mutex_lock(&c->bucket_lock);
>   
> @@ -828,14 +828,19 @@ int bch_btree_cache_alloc(struct cache_set *c)
>   		c->verify_data = NULL;
>   #endif
>   
> -	c->shrink.count_objects = bch_mca_count;
> -	c->shrink.scan_objects = bch_mca_scan;
> -	c->shrink.seeks = 4;
> -	c->shrink.batch = c->btree_pages * 2;
> +	c->shrink = shrinker_alloc(0, "md-bcache:%pU", c->set_uuid);
> +	if (!c->shrink) {
> +		pr_warn("bcache: %s: could not allocate shrinker\n", __func__);
> +		return -ENOMEM;

Seems you have cheanged the semantic of this. In the past,
it is better to have a shrinker, but now it becomes a mandatory.
Right? I don't know if it is acceptable. From my point of view,
just do the cleanup, don't change any behaviour.

> +	}
> +
> +	c->shrink->count_objects = bch_mca_count;
> +	c->shrink->scan_objects = bch_mca_scan;
> +	c->shrink->seeks = 4;
> +	c->shrink->batch = c->btree_pages * 2;
> +	c->shrink->private_data = c;
>   
> -	if (register_shrinker(&c->shrink, "md-bcache:%pU", c->set_uuid))
> -		pr_warn("bcache: %s: could not register shrinker\n",
> -				__func__);
> +	shrinker_register(c->shrink);
>   
>   	return 0;
>   }
> diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
> index 0e2c1880f60b..45d8af755de6 100644
> --- a/drivers/md/bcache/sysfs.c
> +++ b/drivers/md/bcache/sysfs.c
> @@ -866,7 +866,8 @@ STORE(__bch_cache_set)
>   
>   		sc.gfp_mask = GFP_KERNEL;
>   		sc.nr_to_scan = strtoul_or_return(buf);
> -		c->shrink.scan_objects(&c->shrink, &sc);
> +		if (c->shrink)
> +			c->shrink->scan_objects(c->shrink, &sc);
>   	}
>   
>   	sysfs_strtoul_clamp(congested_read_threshold_us,
Qi Zheng July 26, 2023, 9:33 a.m. UTC | #2
On 2023/7/26 15:32, Muchun Song wrote:
> 
> 
> On 2023/7/24 17:43, Qi Zheng wrote:
>> In preparation for implementing lockless slab shrink, use new APIs to
>> dynamically allocate the md-bcache shrinker, so that it can be freed
>> asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
>> read-side critical section when releasing the struct cache_set.
>>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>> ---
>>   drivers/md/bcache/bcache.h |  2 +-
>>   drivers/md/bcache/btree.c  | 27 ++++++++++++++++-----------
>>   drivers/md/bcache/sysfs.c  |  3 ++-
>>   3 files changed, 19 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
>> index 5a79bb3c272f..c622bc50f81b 100644
>> --- a/drivers/md/bcache/bcache.h
>> +++ b/drivers/md/bcache/bcache.h
>> @@ -541,7 +541,7 @@ struct cache_set {
>>       struct bio_set        bio_split;
>>       /* For the btree cache */
>> -    struct shrinker        shrink;
>> +    struct shrinker        *shrink;
>>       /* For the btree cache and anything allocation related */
>>       struct mutex        bucket_lock;
>> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
>> index fd121a61f17c..c176c7fc77d9 100644
>> --- a/drivers/md/bcache/btree.c
>> +++ b/drivers/md/bcache/btree.c
>> @@ -667,7 +667,7 @@ static int mca_reap(struct btree *b, unsigned int 
>> min_order, bool flush)
>>   static unsigned long bch_mca_scan(struct shrinker *shrink,
>>                     struct shrink_control *sc)
>>   {
>> -    struct cache_set *c = container_of(shrink, struct cache_set, 
>> shrink);
>> +    struct cache_set *c = shrink->private_data;
>>       struct btree *b, *t;
>>       unsigned long i, nr = sc->nr_to_scan;
>>       unsigned long freed = 0;
>> @@ -734,7 +734,7 @@ static unsigned long bch_mca_scan(struct shrinker 
>> *shrink,
>>   static unsigned long bch_mca_count(struct shrinker *shrink,
>>                      struct shrink_control *sc)
>>   {
>> -    struct cache_set *c = container_of(shrink, struct cache_set, 
>> shrink);
>> +    struct cache_set *c = shrink->private_data;
>>       if (c->shrinker_disabled)
>>           return 0;
>> @@ -752,8 +752,8 @@ void bch_btree_cache_free(struct cache_set *c)
>>       closure_init_stack(&cl);
>> -    if (c->shrink.list.next)
>> -        unregister_shrinker(&c->shrink);
>> +    if (c->shrink)
>> +        shrinker_unregister(c->shrink);
>>       mutex_lock(&c->bucket_lock);
>> @@ -828,14 +828,19 @@ int bch_btree_cache_alloc(struct cache_set *c)
>>           c->verify_data = NULL;
>>   #endif
>> -    c->shrink.count_objects = bch_mca_count;
>> -    c->shrink.scan_objects = bch_mca_scan;
>> -    c->shrink.seeks = 4;
>> -    c->shrink.batch = c->btree_pages * 2;
>> +    c->shrink = shrinker_alloc(0, "md-bcache:%pU", c->set_uuid);
>> +    if (!c->shrink) {
>> +        pr_warn("bcache: %s: could not allocate shrinker\n", __func__);
>> +        return -ENOMEM;
> 
> Seems you have cheanged the semantic of this. In the past,
> it is better to have a shrinker, but now it becomes a mandatory.
> Right? I don't know if it is acceptable. From my point of view,
> just do the cleanup, don't change any behaviour.

Oh, should return 0 here, will do.

> 
>> +    }
>> +
>> +    c->shrink->count_objects = bch_mca_count;
>> +    c->shrink->scan_objects = bch_mca_scan;
>> +    c->shrink->seeks = 4;
>> +    c->shrink->batch = c->btree_pages * 2;
>> +    c->shrink->private_data = c;
>> -    if (register_shrinker(&c->shrink, "md-bcache:%pU", c->set_uuid))
>> -        pr_warn("bcache: %s: could not register shrinker\n",
>> -                __func__);
>> +    shrinker_register(c->shrink);
>>       return 0;
>>   }
>> diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
>> index 0e2c1880f60b..45d8af755de6 100644
>> --- a/drivers/md/bcache/sysfs.c
>> +++ b/drivers/md/bcache/sysfs.c
>> @@ -866,7 +866,8 @@ STORE(__bch_cache_set)
>>           sc.gfp_mask = GFP_KERNEL;
>>           sc.nr_to_scan = strtoul_or_return(buf);
>> -        c->shrink.scan_objects(&c->shrink, &sc);
>> +        if (c->shrink)
>> +            c->shrink->scan_objects(c->shrink, &sc);
>>       }
>>       sysfs_strtoul_clamp(congested_read_threshold_us,
>
diff mbox series

Patch

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 5a79bb3c272f..c622bc50f81b 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -541,7 +541,7 @@  struct cache_set {
 	struct bio_set		bio_split;
 
 	/* For the btree cache */
-	struct shrinker		shrink;
+	struct shrinker		*shrink;
 
 	/* For the btree cache and anything allocation related */
 	struct mutex		bucket_lock;
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index fd121a61f17c..c176c7fc77d9 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -667,7 +667,7 @@  static int mca_reap(struct btree *b, unsigned int min_order, bool flush)
 static unsigned long bch_mca_scan(struct shrinker *shrink,
 				  struct shrink_control *sc)
 {
-	struct cache_set *c = container_of(shrink, struct cache_set, shrink);
+	struct cache_set *c = shrink->private_data;
 	struct btree *b, *t;
 	unsigned long i, nr = sc->nr_to_scan;
 	unsigned long freed = 0;
@@ -734,7 +734,7 @@  static unsigned long bch_mca_scan(struct shrinker *shrink,
 static unsigned long bch_mca_count(struct shrinker *shrink,
 				   struct shrink_control *sc)
 {
-	struct cache_set *c = container_of(shrink, struct cache_set, shrink);
+	struct cache_set *c = shrink->private_data;
 
 	if (c->shrinker_disabled)
 		return 0;
@@ -752,8 +752,8 @@  void bch_btree_cache_free(struct cache_set *c)
 
 	closure_init_stack(&cl);
 
-	if (c->shrink.list.next)
-		unregister_shrinker(&c->shrink);
+	if (c->shrink)
+		shrinker_unregister(c->shrink);
 
 	mutex_lock(&c->bucket_lock);
 
@@ -828,14 +828,19 @@  int bch_btree_cache_alloc(struct cache_set *c)
 		c->verify_data = NULL;
 #endif
 
-	c->shrink.count_objects = bch_mca_count;
-	c->shrink.scan_objects = bch_mca_scan;
-	c->shrink.seeks = 4;
-	c->shrink.batch = c->btree_pages * 2;
+	c->shrink = shrinker_alloc(0, "md-bcache:%pU", c->set_uuid);
+	if (!c->shrink) {
+		pr_warn("bcache: %s: could not allocate shrinker\n", __func__);
+		return -ENOMEM;
+	}
+
+	c->shrink->count_objects = bch_mca_count;
+	c->shrink->scan_objects = bch_mca_scan;
+	c->shrink->seeks = 4;
+	c->shrink->batch = c->btree_pages * 2;
+	c->shrink->private_data = c;
 
-	if (register_shrinker(&c->shrink, "md-bcache:%pU", c->set_uuid))
-		pr_warn("bcache: %s: could not register shrinker\n",
-				__func__);
+	shrinker_register(c->shrink);
 
 	return 0;
 }
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 0e2c1880f60b..45d8af755de6 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -866,7 +866,8 @@  STORE(__bch_cache_set)
 
 		sc.gfp_mask = GFP_KERNEL;
 		sc.nr_to_scan = strtoul_or_return(buf);
-		c->shrink.scan_objects(&c->shrink, &sc);
+		if (c->shrink)
+			c->shrink->scan_objects(c->shrink, &sc);
 	}
 
 	sysfs_strtoul_clamp(congested_read_threshold_us,