Re: [PATCH 2/4] block: partition: convert percpu ref
On Thu, Jul 16, 2015 at 11:16:45AM +0800, Ming Lei wrote: > Percpu refcount is the perfect match for partition's case, > and the conversion is quite straight. > > With the convertion, one pair of atomic inc/dec can be saved > for accounting block I/O, which is run in hot path of block I/O. > > Signed-off-by: Ming Lei Acked-by: Tejun Heo Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/4] block: partition: convert percpu ref
On Thu, Jul 16, 2015 at 11:16:45AM +0800, Ming Lei wrote: Percpu refcount is the perfect match for partition's case, and the conversion is quite straight. With the convertion, one pair of atomic inc/dec can be saved for accounting block I/O, which is run in hot path of block I/O. Signed-off-by: Ming Lei tom.leim...@gmail.com Acked-by: Tejun Heo t...@kernel.org Thanks. -- tejun -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 2/4] block: partition: convert percpu ref
Percpu refcount is the perfect match for partition's case,
and the conversion is quite straight.
With the convertion, one pair of atomic inc/dec can be saved
for accounting block I/O, which is run in hot path of block I/O.
Signed-off-by: Ming Lei
---
block/genhd.c | 6 +-
block/partition-generic.c | 9 +
include/linux/genhd.h | 27 +--
3 files changed, 27 insertions(+), 15 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index ed3f5b9..3213b66 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1284,7 +1284,11 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
* converted to make use of bd_mutex and sequence counters.
*/
seqcount_init(>part0.nr_sects_seq);
- hd_ref_init(>part0);
+ if (hd_ref_init(>part0)) {
+ hd_free_part(>part0);
+ kfree(disk);
+ return NULL;
+ }
disk->minors = minors;
rand_initialize_disk(disk);
diff --git a/block/partition-generic.c b/block/partition-generic.c
index eca0d02..e771113 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -232,8 +232,9 @@ static void delete_partition_rcu_cb(struct rcu_head *head)
put_device(part_to_dev(part));
}
-void __delete_partition(struct hd_struct *part)
+void __delete_partition(struct percpu_ref *ref)
{
+ struct hd_struct *part = container_of(ref, struct hd_struct, ref);
call_rcu(>rcu_head, delete_partition_rcu_cb);
}
@@ -254,7 +255,7 @@ void delete_partition(struct gendisk *disk, int partno)
kobject_put(part->holder_dir);
device_del(part_to_dev(part));
- hd_struct_put(part);
+ hd_struct_kill(part);
}
static ssize_t whole_disk_show(struct device *dev,
@@ -355,8 +356,8 @@ struct hd_struct *add_partition(struct gendisk *disk, int
partno,
if (!dev_get_uevent_suppress(ddev))
kobject_uevent(>kobj, KOBJ_ADD);
- hd_ref_init(p);
- return p;
+ if (!hd_ref_init(p))
+ return p;
out_free_info:
free_part_info(p);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index a221220..2adbfa6 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -13,6 +13,7 @@
#include
#include
#include
+#include
#ifdef CONFIG_BLOCK
@@ -124,7 +125,7 @@ struct hd_struct {
#else
struct disk_stats dkstats;
#endif
- atomic_t ref;
+ struct percpu_ref ref;
struct rcu_head rcu_head;
};
@@ -611,7 +612,7 @@ extern struct hd_struct * __must_check add_partition(struct
gendisk *disk,
sector_t len, int flags,
struct partition_meta_info
*info);
-extern void __delete_partition(struct hd_struct *);
+extern void __delete_partition(struct percpu_ref *);
extern void delete_partition(struct gendisk *, int);
extern void printk_all_partitions(void);
@@ -640,33 +641,39 @@ extern ssize_t part_fail_store(struct device *dev,
const char *buf, size_t count);
#endif /* CONFIG_FAIL_MAKE_REQUEST */
-static inline void hd_ref_init(struct hd_struct *part)
+static inline int hd_ref_init(struct hd_struct *part)
{
- atomic_set(>ref, 1);
- smp_mb();
+ if (percpu_ref_init(>ref, __delete_partition, 0,
+ GFP_KERNEL))
+ return -ENOMEM;
+ return 0;
}
static inline void hd_struct_get(struct hd_struct *part)
{
- atomic_inc(>ref);
- smp_mb__after_atomic();
+ percpu_ref_get(>ref);
}
static inline int hd_struct_try_get(struct hd_struct *part)
{
- return atomic_inc_not_zero(>ref);
+ return percpu_ref_tryget_live(>ref);
}
static inline void hd_struct_put(struct hd_struct *part)
{
- if (atomic_dec_and_test(>ref))
- __delete_partition(part);
+ percpu_ref_put(>ref);
+}
+
+static inline void hd_struct_kill(struct hd_struct *part)
+{
+ percpu_ref_kill(>ref);
}
static inline void hd_free_part(struct hd_struct *part)
{
free_part_stats(part);
free_part_info(part);
+ percpu_ref_exit(>ref);
}
/*
--
1.9.1
--
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[PATCH 2/4] block: partition: convert percpu ref
Percpu refcount is the perfect match for partition's case,
and the conversion is quite straight.
With the convertion, one pair of atomic inc/dec can be saved
for accounting block I/O, which is run in hot path of block I/O.
Signed-off-by: Ming Lei tom.leim...@gmail.com
---
block/genhd.c | 6 +-
block/partition-generic.c | 9 +
include/linux/genhd.h | 27 +--
3 files changed, 27 insertions(+), 15 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index ed3f5b9..3213b66 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1284,7 +1284,11 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
* converted to make use of bd_mutex and sequence counters.
*/
seqcount_init(disk-part0.nr_sects_seq);
- hd_ref_init(disk-part0);
+ if (hd_ref_init(disk-part0)) {
+ hd_free_part(disk-part0);
+ kfree(disk);
+ return NULL;
+ }
disk-minors = minors;
rand_initialize_disk(disk);
diff --git a/block/partition-generic.c b/block/partition-generic.c
index eca0d02..e771113 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -232,8 +232,9 @@ static void delete_partition_rcu_cb(struct rcu_head *head)
put_device(part_to_dev(part));
}
-void __delete_partition(struct hd_struct *part)
+void __delete_partition(struct percpu_ref *ref)
{
+ struct hd_struct *part = container_of(ref, struct hd_struct, ref);
call_rcu(part-rcu_head, delete_partition_rcu_cb);
}
@@ -254,7 +255,7 @@ void delete_partition(struct gendisk *disk, int partno)
kobject_put(part-holder_dir);
device_del(part_to_dev(part));
- hd_struct_put(part);
+ hd_struct_kill(part);
}
static ssize_t whole_disk_show(struct device *dev,
@@ -355,8 +356,8 @@ struct hd_struct *add_partition(struct gendisk *disk, int
partno,
if (!dev_get_uevent_suppress(ddev))
kobject_uevent(pdev-kobj, KOBJ_ADD);
- hd_ref_init(p);
- return p;
+ if (!hd_ref_init(p))
+ return p;
out_free_info:
free_part_info(p);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index a221220..2adbfa6 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -13,6 +13,7 @@
#include linux/kdev_t.h
#include linux/rcupdate.h
#include linux/slab.h
+#include linux/percpu-refcount.h
#ifdef CONFIG_BLOCK
@@ -124,7 +125,7 @@ struct hd_struct {
#else
struct disk_stats dkstats;
#endif
- atomic_t ref;
+ struct percpu_ref ref;
struct rcu_head rcu_head;
};
@@ -611,7 +612,7 @@ extern struct hd_struct * __must_check add_partition(struct
gendisk *disk,
sector_t len, int flags,
struct partition_meta_info
*info);
-extern void __delete_partition(struct hd_struct *);
+extern void __delete_partition(struct percpu_ref *);
extern void delete_partition(struct gendisk *, int);
extern void printk_all_partitions(void);
@@ -640,33 +641,39 @@ extern ssize_t part_fail_store(struct device *dev,
const char *buf, size_t count);
#endif /* CONFIG_FAIL_MAKE_REQUEST */
-static inline void hd_ref_init(struct hd_struct *part)
+static inline int hd_ref_init(struct hd_struct *part)
{
- atomic_set(part-ref, 1);
- smp_mb();
+ if (percpu_ref_init(part-ref, __delete_partition, 0,
+ GFP_KERNEL))
+ return -ENOMEM;
+ return 0;
}
static inline void hd_struct_get(struct hd_struct *part)
{
- atomic_inc(part-ref);
- smp_mb__after_atomic();
+ percpu_ref_get(part-ref);
}
static inline int hd_struct_try_get(struct hd_struct *part)
{
- return atomic_inc_not_zero(part-ref);
+ return percpu_ref_tryget_live(part-ref);
}
static inline void hd_struct_put(struct hd_struct *part)
{
- if (atomic_dec_and_test(part-ref))
- __delete_partition(part);
+ percpu_ref_put(part-ref);
+}
+
+static inline void hd_struct_kill(struct hd_struct *part)
+{
+ percpu_ref_kill(part-ref);
}
static inline void hd_free_part(struct hd_struct *part)
{
free_part_stats(part);
free_part_info(part);
+ percpu_ref_exit(part-ref);
}
/*
--
1.9.1
--
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