Re: [PATCH 1/2] mem_cgroup: optimize the atomic count of wb_completion

From: Michal Hocko
Date: Fri Sep 24 2021 - 05:34:29 EST

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?
Michal Hocko