If flush commands do not incur any congestion, we don't need to throw that to dispatching queue which causes unnecessary latency.
Signed-off-by: Jaegeuk Kim <[email protected]> --- fs/f2fs/f2fs.h | 1 + fs/f2fs/segment.c | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 917cc9b..97cd3c8 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -603,6 +603,7 @@ struct flush_cmd { struct flush_cmd_control { struct task_struct *f2fs_issue_flush; /* flush thread */ wait_queue_head_t flush_wait_queue; /* waiting queue for wake-up */ + atomic_t submit_flush; /* # of issued flushes */ struct llist_head issue_list; /* list for command issue */ struct llist_node *dispatch_list; /* list for command dispatch */ }; diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 77dc929..34a9159 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -433,24 +433,28 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi) if (test_opt(sbi, NOBARRIER)) return 0; - if (!test_opt(sbi, FLUSH_MERGE)) { + if (!test_opt(sbi, FLUSH_MERGE) || !atomic_read(&fcc->submit_flush)) { struct bio *bio = f2fs_bio_alloc(0); int ret; + atomic_inc(&fcc->submit_flush); bio->bi_bdev = sbi->sb->s_bdev; ret = submit_bio_wait(WRITE_FLUSH, bio); + atomic_dec(&fcc->submit_flush); bio_put(bio); return ret; } init_completion(&cmd.wait); + atomic_inc(&fcc->submit_flush); llist_add(&cmd.llnode, &fcc->issue_list); if (!fcc->dispatch_list) wake_up(&fcc->flush_wait_queue); wait_for_completion(&cmd.wait); + atomic_dec(&fcc->submit_flush); return cmd.ret; } @@ -464,6 +468,7 @@ int create_flush_cmd_control(struct f2fs_sb_info *sbi) fcc = kzalloc(sizeof(struct flush_cmd_control), GFP_KERNEL); if (!fcc) return -ENOMEM; + atomic_set(&fcc->submit_flush, 0); init_waitqueue_head(&fcc->flush_wait_queue); init_llist_head(&fcc->issue_list); SM_I(sbi)->cmd_control_info = fcc; -- 2.6.3
