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@xxxxxxxxx>
---
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
