diff mbox series

[2/4] ext4: drop s_mb_bal_lock and convert protected fields to atomic

Message ID 20210129222931.623008-3-harshadshirwadkar@gmail.com
State New
Headers show
Series Improve group scanning in CR 0 and CR 1 passes | expand

Commit Message

harshad shirwadkar Jan. 29, 2021, 10:29 p.m. UTC
s_mb_buddies_generated gets used later in this patch series to
determine if the cr 0 and cr 1 optimziations should be performed or
not. Currently, s_mb_buddies_generated is protected under a
spin_lock. In the allocation path, it is better if we don't depend on
the lock and instead read the value atomically. In order to do that,
we drop s_bal_lock altogether and we convert the only two protected
fields by it s_mb_buddies_generated and s_mb_generation_time to atomic
type.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
---
 fs/ext4/ext4.h    |  5 ++---
 fs/ext4/mballoc.c | 13 +++++--------
 2 files changed, 7 insertions(+), 11 deletions(-)

Comments

Andreas Dilger Jan. 30, 2021, 8:38 a.m. UTC | #1
On Jan 29, 2021, at 3:29 PM, Harshad Shirwadkar <harshadshirwadkar@gmail.com> wrote:
> 
> s_mb_buddies_generated gets used later in this patch series to
> determine if the cr 0 and cr 1 optimziations should be performed or
> not. Currently, s_mb_buddies_generated is protected under a
> spin_lock. In the allocation path, it is better if we don't depend on
> the lock and instead read the value atomically. In order to do that,
> we drop s_bal_lock altogether and we convert the only two protected
> fields by it s_mb_buddies_generated and s_mb_generation_time to atomic
> type.
> 
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> fs/ext4/ext4.h    |  5 ++---
> fs/ext4/mballoc.c | 13 +++++--------
> 2 files changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 64f25ea2fa7a..6dd127942208 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1552,9 +1552,8 @@ struct ext4_sb_info {
> 	atomic_t s_bal_goals;	/* goal hits */
> 	atomic_t s_bal_breaks;	/* too long searches */
> 	atomic_t s_bal_2orders;	/* 2^order hits */
> -	spinlock_t s_bal_lock;
> -	unsigned long s_mb_buddies_generated;
> -	unsigned long long s_mb_generation_time;
> +	atomic_t s_mb_buddies_generated;	/* number of buddies generated */
> +	atomic64_t s_mb_generation_time;
> 	atomic_t s_mb_lost_chunks;
> 	atomic_t s_mb_preallocated;
> 	atomic_t s_mb_discarded;
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 625242e5c683..11c56b0e6f35 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -816,10 +816,8 @@ void ext4_mb_generate_buddy(struct super_block *sb,
> 	clear_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
> 
> 	period = get_cycles() - period;
> -	spin_lock(&sbi->s_bal_lock);
> -	sbi->s_mb_buddies_generated++;
> -	sbi->s_mb_generation_time += period;
> -	spin_unlock(&sbi->s_bal_lock);
> +	atomic_inc(&sbi->s_mb_buddies_generated);
> +	atomic64_add(period, &sbi->s_mb_generation_time);
> }
> 
> /* The buddy information is attached the buddy cache inode
> @@ -2844,7 +2842,6 @@ int ext4_mb_init(struct super_block *sb)
> 
> 
> 	spin_lock_init(&sbi->s_md_lock);
> -	spin_lock_init(&sbi->s_bal_lock);
> 	sbi->s_mb_free_pending = 0;
> 	INIT_LIST_HEAD(&sbi->s_freed_data_list);
> 
> @@ -2980,9 +2977,9 @@ int ext4_mb_release(struct super_block *sb)
> 				atomic_read(&sbi->s_bal_breaks),
> 				atomic_read(&sbi->s_mb_lost_chunks));
> 		ext4_msg(sb, KERN_INFO,
> -		       "mballoc: %lu generated and it took %Lu",
> -				sbi->s_mb_buddies_generated,
> -				sbi->s_mb_generation_time);
> +		       "mballoc: %u generated and it took %llu",
> +				atomic_read(&sbi->s_mb_buddies_generated),
> +				atomic64_read(&sbi->s_mb_generation_time));
> 		ext4_msg(sb, KERN_INFO,
> 		       "mballoc: %u preallocated, %u discarded",
> 				atomic_read(&sbi->s_mb_preallocated),
> --
> 2.30.0.365.g02bc693789-goog
> 


Cheers, Andreas
diff mbox series

Patch

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 64f25ea2fa7a..6dd127942208 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1552,9 +1552,8 @@  struct ext4_sb_info {
 	atomic_t s_bal_goals;	/* goal hits */
 	atomic_t s_bal_breaks;	/* too long searches */
 	atomic_t s_bal_2orders;	/* 2^order hits */
-	spinlock_t s_bal_lock;
-	unsigned long s_mb_buddies_generated;
-	unsigned long long s_mb_generation_time;
+	atomic_t s_mb_buddies_generated;	/* number of buddies generated */
+	atomic64_t s_mb_generation_time;
 	atomic_t s_mb_lost_chunks;
 	atomic_t s_mb_preallocated;
 	atomic_t s_mb_discarded;
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 625242e5c683..11c56b0e6f35 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -816,10 +816,8 @@  void ext4_mb_generate_buddy(struct super_block *sb,
 	clear_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
 
 	period = get_cycles() - period;
-	spin_lock(&sbi->s_bal_lock);
-	sbi->s_mb_buddies_generated++;
-	sbi->s_mb_generation_time += period;
-	spin_unlock(&sbi->s_bal_lock);
+	atomic_inc(&sbi->s_mb_buddies_generated);
+	atomic64_add(period, &sbi->s_mb_generation_time);
 }
 
 /* The buddy information is attached the buddy cache inode
@@ -2844,7 +2842,6 @@  int ext4_mb_init(struct super_block *sb)
 
 
 	spin_lock_init(&sbi->s_md_lock);
-	spin_lock_init(&sbi->s_bal_lock);
 	sbi->s_mb_free_pending = 0;
 	INIT_LIST_HEAD(&sbi->s_freed_data_list);
 
@@ -2980,9 +2977,9 @@  int ext4_mb_release(struct super_block *sb)
 				atomic_read(&sbi->s_bal_breaks),
 				atomic_read(&sbi->s_mb_lost_chunks));
 		ext4_msg(sb, KERN_INFO,
-		       "mballoc: %lu generated and it took %Lu",
-				sbi->s_mb_buddies_generated,
-				sbi->s_mb_generation_time);
+		       "mballoc: %u generated and it took %llu",
+				atomic_read(&sbi->s_mb_buddies_generated),
+				atomic64_read(&sbi->s_mb_generation_time));
 		ext4_msg(sb, KERN_INFO,
 		       "mballoc: %u preallocated, %u discarded",
 				atomic_read(&sbi->s_mb_preallocated),