Commit a1395abb authored Jun 21, 2018 by Yunlei He Committed by Jaegeuk Kim Sep 18, 2018

f2fs: fix a hungtask problem caused by congestion_wait



This patch fix hungtask problem which can be reproduced as follow:

Thread 0~3:
while true
do
        touch /xxx/test/file_xxx
done

Thread 4 write a new checkpoint every three seconds.

In the meantime, fio start 16 threads for randwrite.

With my debug info, cycles num will exceed 1000 in function
f2fs_sync_dirty_inodes, and most of cycle will be dropped
into congestion_wait() and sleep more than 20ms. Cycles num
reduced to 3 with this patch.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

parent 7eacb5df

fs/f2fs/checkpoint.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -972,12 +972,10 @@ int f2fs_sync_dirty_inodes(struct f2fs_sb_info *sbi, enum inode_type type)

		iput(inode);
		/* We need to give cpu to another writers. */
		if (ino == cur_ino) {
		congestion_wait(BLK_RW_ASYNC, HZ/50);
		if (ino == cur_ino)
		cond_resched();
		} else {
		else
		ino = cur_ino;
		}
		} else {
		/*
		* We should submit bio, since it exists several