Hi all, Cgroup writeback is supported since v4.2. I found there exists a problem in the following case.
A cgroup may send both buffer and direct/sync IOs. The foreground thread will be stalled when periodic writeback IOs is flushed because the service queue already has a plenty of writeback IOs, then foreground IOs should be enqueued with its FIFO policy. I wonder if we can distinguish foreground and background IOs in block throttle to fix the above problem. Any suggestion are always appreciated. Thanks, Jiufei
