linux-kernel - Re: [PATCH v5 1/2] mm: store zero pages to be swapped out in a bitmap

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Date: Fri, 14 Jun 2024 11:36:10 -0700
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Usama Arif <usamaarif642@...il.com>
Cc: akpm@...ux-foundation.org, hannes@...xchg.org, shakeel.butt@...ux.dev, 
	david@...hat.com, ying.huang@...el.com, hughd@...gle.com, willy@...radead.org, 
	nphamcs@...il.com, chengming.zhou@...ux.dev, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, kernel-team@...a.com
Subject: Re: [PATCH v5 1/2] mm: store zero pages to be swapped out in a bitmap

On Fri, Jun 14, 2024 at 3:09 AM Usama Arif <usamaarif642@...il.com> wrote:
>
> Approximately 10-20% of pages to be swapped out are zero pages [1].
> Rather than reading/writing these pages to flash resulting
> in increased I/O and flash wear, a bitmap can be used to mark these
> pages as zero at write time, and the pages can be filled at
> read time if the bit corresponding to the page is set.
> With this patch, NVMe writes in Meta server fleet decreased
> by almost 10% with conventional swap setup (zswap disabled).
>
> [1] https://lore.kernel.org/all/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1/
>
> Signed-off-by: Usama Arif <usamaarif642@...il.com>

Reviewed-by: Yosry Ahmed <yosryahmed@...gle.com>