f2fs: detect congestion of flush command issues
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 <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index bf1c8b0..f02a357 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -603,6 +603,7 @@
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 @@
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 @@
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;