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

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Message-ID: <CAJD7tkZY-VNGbekQsB8UdMhyN60zdg0DnjomzwSi77+Jv+N1Zw@mail.gmail.com>
Date: Thu, 29 Aug 2024 16:55:22 -0700
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Nhat Pham <nphamcs@...il.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, 
	Shakeel Butt <shakeel.butt@...ux.dev>
Subject: Re: [PATCH v5 0/3] mm: ZSWAP swap-out of mTHP folios

On Thu, Aug 29, 2024 at 4:48 PM Nhat Pham <nphamcs@...il.com> wrote:
>
> On Thu, Aug 29, 2024 at 4:39 PM Yosry Ahmed <yosryahmed@...gle.com> wrote:
> >
> > Interesting. If CONFIG_THP_SWAP is enabled this basically means your
> > zswap utilization keeps going down as your THP utilization goes up. So
> > the swapin cost would go higher. How do you deal with that?
>
> Johannes definitely knows more than me about this, so please fact
> check me. But my understanding is we don't get enough THP for this to
> become a problem just yet :)
>
> But yes, we're working hard to make THP become more readily available.
> Which will lead to the problem you're describing, hence my enthusiasm
> in this work :)

Adding Shakeel here as well as I am sure he's familiar with the
problem I was talking about.