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>
This commit is contained in:
Yunlei He 2018-06-21 14:49:06 +08:00 committed by Jaegeuk Kim
parent 2a96d8ad94
commit 2a63531a61

View file

@ -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