Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 24 Mar 2022 10:51:57 +0100
From:   Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
To:     Roman Gushchin <roman.gushchin@linux.dev>
Cc:     cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Richard Palethorpe <rpalethorpe@suse.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Shakeel Butt <shakeelb@google.com>,
        Michal Hocko <mhocko@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Muchun Song <songmuchun@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Yang Shi <shy828301@gmail.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Tejun Heo <tj@kernel.org>, Chris Down <chris@chrisdown.name>
Subject: Re: [RFC PATCH] mm: memcg: Do not count memory.low reclaim if it
 does not happen
Message-ID: <20220324095157.GA16685@blackbody.suse.cz>
References: <20220322182248.29121-1-mkoutny@suse.com>
 <YjuUuLW+8iRtYOmP@carbon.dhcp.thefacebook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YjuUuLW+8iRtYOmP@carbon.dhcp.thefacebook.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk

On Wed, Mar 23, 2022 at 02:44:24PM -0700, Roman Gushchin <roman.gushchin@linux.dev> wrote:
> Does it mean that in the following configuration:
> 	`parent .low=50M
> 	  ` s1	.low=0M   .current=50M
> 	  ` s2  .low=0M   .current=50M
> there will be no memory.events::low at all? (assuming the recursive thing is on)

True, no memory.events:low among siblings.
Number of memory.events:low in the parent depends on how much has to be
reclaimed (>50M means carving into parent's protection, hence it'll be
counted).

This is a quantitative change in the events reporting (point 1 of
RFCness), my understanding is that the potential events due to recursive
surplus protection carry no new information regarding configured
memory.low.


Michal