Thanks for your time. Michal Hocko wrote on 2021/9/24 17:34: > On Fri 24-09-21 14:46:22, brookxu wrote: >> From: Chunguang Xu <brookxu@xxxxxxxxxxx> >> >> In order to track inflight foreign writeback, we init >> wb_completion.cnt to 1. For normal writeback, this cause >> wb_wait_for_completion() to perform meaningless atomic >> operations. Since foreign writebacks rarely occur in most >> scenarios, we can init wb_completion.cnt to 0 and set >> frn.done.cnt to 1. In this way we can avoid unnecessary >> atomic operations. > > Does this lead to any measurable differences? I created multiple cgroups that performed IO on multiple disks, then flushed the cache with sync command, and no measurable differences have been observed so far. >
