linux-kernel - Re: [PATCH v2 3/3] mm: rmap: support batched unmapping for file large folios

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Message-ID: <CAGsJ_4yVCbP9EJ2KZu-83PL-LViB+zn3NPC5E61LKf+nWWNsWw@mail.gmail.com>
Date: Thu, 11 Dec 2025 20:36:51 +0800
From: Barry Song <21cnbao@...il.com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: akpm@...ux-foundation.org, david@...nel.org, catalin.marinas@....com, 
	will@...nel.org, lorenzo.stoakes@...cle.com, ryan.roberts@....com, 
	Liam.Howlett@...cle.com, vbabka@...e.cz, rppt@...nel.org, surenb@...gle.com, 
	mhocko@...e.com, riel@...riel.com, harry.yoo@...cle.com, jannh@...gle.com, 
	willy@...radead.org, linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] mm: rmap: support batched unmapping for file large folios

On Thu, Dec 11, 2025 at 4:17 PM Baolin Wang
<baolin.wang@...ux.alibaba.com> wrote:
>
> Similar to folio_referenced_one(), we can apply batched unmapping for file
> large folios to optimize the performance of file folios reclamation.
>
> Performance testing:
> Allocate 10G clean file-backed folios by mmap() in a memory cgroup, and try to
> reclaim 8G file-backed folios via the memory.reclaim interface. I can observe
> 75% performance improvement on my Arm64 32-core server.
>
> W/o patch:
> real    0m1.018s
> user    0m0.000s
> sys     0m1.018s
>
> W/ patch:
> real    0m0.249s
> user    0m0.000s
> sys     0m0.249s
>
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

It appears quite straightforward to introduce file folios support based on the
current lazyfree implementation.

Acked-by: Barry Song <baohua@...nel.org>