From: Yu Chao <chao2.yu@xxxxxxxxxxx>
There is a performance problem: when all sbi->fs_lock are holded, then
all the following threads may get the same next_lock value from sbi->next_lock_num
in function mutex_lock_op, and wait for the same lock(fs_lock[next_lock]),
it may cause performance reduce.
So we move the sbi->next_lock_num++ before getting lock, this will average the
following threads if all sbi->fs_lock are holded.
v1-->v2:
Drop the needless spin_lock as Jaegeuk suggested.
Suggested-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
Signed-off-by: Yu Chao <chao2.yu@xxxxxxxxxxx>
Signed-off-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
---
fs/f2fs/f2fs.h | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 608f0df..7fd99d8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -544,15 +544,15 @@ static inline void mutex_unlock_all(struct f2fs_sb_info *sbi)
static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
{
- unsigned char next_lock = sbi->next_lock_num % NR_GLOBAL_LOCKS;
+ unsigned char next_lock;
int i = 0;
for (; i < NR_GLOBAL_LOCKS; i++)
if (mutex_trylock(&sbi->fs_lock[i]))
return i;
+ next_lock = sbi->next_lock_num++ % NR_GLOBAL_LOCKS;
mutex_lock(&sbi->fs_lock[next_lock]);
- sbi->next_lock_num++;
return next_lock;
}
--
1.7.7
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
