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References: <20240614100902.3469724-1-usamaarif642@gmail.com> <20240614100902.3469724-2-usamaarif642@gmail.com>
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From: Yosry Ahmed <yosryahmed@google.com>
Date: Fri, 14 Jun 2024 11:36:10 -0700
Message-ID: <CAJD7tkatLV61SaZzHOw7r9+XjYsOhGn4yw78QOW-6foFiap8_g@mail.gmail.com>
Subject: Re: [PATCH v5 1/2] mm: store zero pages to be swapped out in a bitmap
To: Usama Arif <usamaarif642@gmail.com>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, shakeel.butt@linux.dev, 
	david@redhat.com, ying.huang@intel.com, hughd@google.com, willy@infradead.org, 
	nphamcs@gmail.com, chengming.zhou@linux.dev, linux-mm@kvack.org, 
	linux-kernel@vger.kernel.org, kernel-team@meta.com
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On Fri, Jun 14, 2024 at 3:09=E2=80=AFAM Usama Arif <usamaarif642@gmail.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/20171018104832epcms5p1b2232e2236258de3d03=
d1344dde9fce0@epcms5p1/
>
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>

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