linux-kernel - Re: [PATCH v5 0/3] mm: ZSWAP swap-out of mTHP folios

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAKEwX=O8CfyBHZD6Xm_0DW5EuTY7g7FhKHiKj4xzZ4ozxdgQFA@mail.gmail.com>
Date: Thu, 29 Aug 2024 16:33:24 -0700
From: Nhat Pham <nphamcs@...il.com>
To: Yosry Ahmed <yosryahmed@...gle.com>
Cc: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, hannes@...xchg.org, ryan.roberts@....com, 
	ying.huang@...el.com, 21cnbao@...il.com, akpm@...ux-foundation.org, 
	nanhai.zou@...el.com, wajdi.k.feghali@...el.com, vinodh.gopal@...el.com
Subject: Re: [PATCH v5 0/3] mm: ZSWAP swap-out of mTHP folios

On Wed, Aug 28, 2024 at 3:38 PM Yosry Ahmed <yosryahmed@...gle.com> wrote:
>
> On Wed, Aug 28, 2024 at 2:35 AM Kanchana P Sridhar
> <kanchana.p.sridhar@...el.com> wrote:
> Are you saying that in the "Before" data we end up skipping zswap
> completely because of using mTHPs?
>
> Does it make more sense to turn CONFIG_THP_SWAP in the "Before" data
> to force the mTHPs to be split and for the data to be stored in zswap?
> This would be a more fair Before/After comparison where the memory
> goes to zswap in both cases, but "Before" has to be split because of
> zswap's lack of support for mTHP. I assume most setups relying on
> zswap will be turning CONFIG_THP_SWAP off today anyway, but maybe not.
> Nhat, is this something you can share?

I think we're enabling it, but we're a zswap heavy shop + THP
allocation is not suuuper reliable until recently with Johannes'
latest (and upcoming) work, so I don't have much data to share :)