linux-kernel - Re: [PATCH 2/2] mm: move the high field from struct mem_cgroup to page

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Message-ID: <20180423124145.GA29016@castle.DHCP.thefacebook.com>
Date:   Mon, 23 Apr 2018 13:41:51 +0100
From:   Roman Gushchin <guro@...com>
To:     Johannes Weiner <hannes@...xchg.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <cgroups@...r.kernel.org>, <kernel-team@...com>,
        Michal Hocko <mhocko@...e.com>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 2/2] mm: move the high field from struct mem_cgroup to
 page_counter

On Fri, Apr 20, 2018 at 04:54:50PM -0400, Johannes Weiner wrote:
> On Fri, Apr 20, 2018 at 05:36:32PM +0100, Roman Gushchin wrote:
> > We do store memory.min, memory.low and memory.max actual values
> > in struct page_counter fields, while memory.high value is located
> > in the struct mem_cgroup directly, which is not very consistent.
> > 
> > This patch moves the high field from struct mem_cgroup to
> > struct page_counter to simplify the code and make handling
> > of all limits/boundaries clearer.
> 
> I would prefer not doing this.
> 
> Yes, it looks a bit neater if all these things are next to each other
> in the struct, but on the other hand it separates the high variable
> from high_work, and it adds an unnecessary setter function as well.
> 
> Plus, nothing in the page_counter code actually uses the value, it
> really isn't part of that abstraction layer.
> 

Ok, not a problem.
It's nice to have all 4 limits in one place, but separating
high and high_work isn't good, I agree. Let's leave it as it is.

Thanks!