linux-kernel - Re: [PATCH 1/2] mem_cgroup: optimize the atomic count of wb

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Message-ID: <YU2boTZhfbo0h/Xi@dhcp22.suse.cz>
Date:   Fri, 24 Sep 2021 11:34:25 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     brookxu <brookxu.cn@...il.com>
Cc:     hannes@...xchg.org, vdavydov.dev@...il.com,
        akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org
Subject: Re: [PATCH 1/2] mem_cgroup: optimize the atomic count of
 wb_completion

On Fri 24-09-21 14:46:22, brookxu wrote:
> From: Chunguang Xu <brookxu@...cent.com>
> 
> 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
SUSE Labs