Hello, On Thu, May 09, 2019 at 04:03:53PM +0800, zhangliguang wrote: > There might have tons of files queued in the writeback, awaiting for > writing back. Unfortunately, the writeback's cgroup has been dead. In > this case, we reassociate the inode with another writeback cgroup, but > we possibly can't because the writeback associated with the dead cgroup > is the only valid one. In this case, the new writeback is allocated, > initialized and associated with the inode. It causes unnecessary high > system load and latency. > > This fixes the issue by enforce moving the inode to root cgroup when the > previous binding cgroup becomes dead. With it, no more unnecessary > writebacks are created, populated and the system load decreased by about > 6x in the online service we encounted: > Without the patch: about 30% system load > With the patch: about 5% system load Can you please describe the scenario with more details? I'm having a bit of hard time understanding the amount of cpu cycles being consumed. Thanks. -- tejun
