linux-kernel - Re: [PATCH 1/2] mm: list_lru: disable memcg_aware when cgroup.memory is set to "nokmem"

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Message-ID: <ZZS-IFA6TScotocU@P9FQF9L96D>
Date: Tue, 2 Jan 2024 17:53:36 -0800
From: Roman Gushchin <roman.gushchin@...ux.dev>
To: Haifeng Xu <haifeng.xu@...pee.com>
Cc: akpm@...ux-foundation.org, hannes@...xchg.org, mhocko@...nel.org,
	shakeelb@...gle.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: list_lru: disable memcg_aware when cgroup.memory
 is set to "nokmem"

On Thu, Dec 28, 2023 at 06:27:14AM +0000, Haifeng Xu wrote:
> Actually, when using a boot time kernel option "cgroup.memory=nokmem",
> all lru items are inserted to list_lru_node. But for those users who
> invoke list_lru_init_memcg() to initialize list_lru, list_lru_memcg_aware()
> returns true. And this brings unneeded operations related to memcg.
> 
> To make things more convenient, let's disable memcg_aware when
> cgroup.memory is set to "nokmem".

I guess it's not only more convenient, but also should save a bit of memory.
But _probably_ not enough to justify messing up with stable backports.
Do you have any data on memory savings?

> 
> Signed-off-by: Haifeng Xu <haifeng.xu@...pee.com>

Acked-by: Roman Gushchin <roman.gushchin@...ux.dev>

Thanks!