linux-kernel - Re: Re: Re: [PATCH] mm: memcg: Use larger chunks for proactive reclaim

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Date: Fri, 2 Feb 2024 20:46:56 +0100
From: Michal Koutný <mkoutny@...e.com>
To: "T.J. Mercier" <tjmercier@...gle.com>
Cc: Efly Young <yangyifei03@...ishou.com>, hannes@...xchg.org, 
	akpm@...ux-foundation.org, android-mm@...gle.com, cgroups@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, mhocko@...nel.org, muchun.song@...ux.dev, 
	roman.gushchin@...ux.dev, shakeelb@...gle.com, yuzhao@...gle.com
Subject: Re: Re: Re: [PATCH] mm: memcg: Use larger chunks for proactive
 reclaim

On Fri, Feb 02, 2024 at 10:22:34AM -0800, "T.J. Mercier" <tjmercier@...gle.com> wrote:
> So all of these should be more or less equivalent:
> delta <= SWAP_CLUSTER_MAX ? delta : (delta + 3*SWAP_CLUSTER_MAX) / 4
> max((nr_to_reclaim - nr_reclaimed) / 4, (nr_to_reclaim - nr_reclaimed) % 4)
> (nr_to_reclaim - nr_reclaimed) / 4 + 4
> (nr_to_reclaim - nr_reclaimed) / 4
> 
> I was just trying to avoid putting in a 0 for the request size with the mod.

The third variant would be simpler then. Modulo looks weird.

Oh, and I just realized that try_to_free_mem_cgroup_pages() does
max(nr_pages, SWAP_CLUSTER_MAX). Then I'd vote for the fourth variant +
possible comment about harmless 0.
(I'm sorry if this was discussed before.)

Michal

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