From e76eebee70948060d80b5f9edd2d97062049df53 Mon Sep 17 00:00:00 2001 From: Yu Chao Date: Thu, 12 Sep 2013 11:17:51 +0800 Subject: [PATCH] f2fs: optimize fs_lock for better performance 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 Signed-off-by: Yu Chao Signed-off-by: Gu Zheng Signed-off-by: Jaegeuk Kim --- fs/f2fs/f2fs.h | 4 ++-- 1 file 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; } -- 2.7.4