On Fri 24-09-21 21:02:52, brookxu wrote: > 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. OK, so why do we want to optimize this code? -- Michal Hocko SUSE Labs
