linux-kernel - Re: [PATCH v5 4/4] mm: Introduce per-thpsize swapin control policy

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Message-ID: <CAGsJ_4wfWYGZVouK4JTj9DBDNPKTX_zrfU45iivaUy-Nq-P1bA@mail.gmail.com>
Date: Tue, 30 Jul 2024 08:11:16 +1200
From: Barry Song <21cnbao@...il.com>
To: Christoph Hellwig <hch@...radead.org>
Cc: Matthew Wilcox <willy@...radead.org>, akpm@...ux-foundation.org, linux-mm@...ck.org, 
	ying.huang@...el.com, baolin.wang@...ux.alibaba.com, chrisl@...nel.org, 
	david@...hat.com, hannes@...xchg.org, hughd@...gle.com, 
	kaleshsingh@...gle.com, kasong@...cent.com, linux-kernel@...r.kernel.org, 
	mhocko@...e.com, minchan@...nel.org, nphamcs@...il.com, ryan.roberts@....com, 
	senozhatsky@...omium.org, shakeel.butt@...ux.dev, shy828301@...il.com, 
	surenb@...gle.com, v-songbaohua@...o.com, xiang@...nel.org, 
	yosryahmed@...gle.com
Subject: Re: [PATCH v5 4/4] mm: Introduce per-thpsize swapin control policy

On Tue, Jul 30, 2024 at 4:11 AM Christoph Hellwig <hch@...radead.org> wrote:
>
> On Mon, Jul 29, 2024 at 04:52:30AM +0100, Matthew Wilcox wrote:
> > I strongly disagree.  Use the same sysctl as the other anonymous memory
> > allocations.
>
> I agree with Matthew here.

The whole anonymous memory allocation control is still used here. this is
just an addition: anonymous memory allocation control & swapin policy,
primarily for addressing SSD concern not for zRAM in the original v4's
comment.

>
> We also really need to stop optimizing for this weird zram case and move
> people to zswap instead after fixing the various issues.  A special
> block device that isn't really a block device and needs various special
> hooks isn't the right abstraction for different zwap strategies.

My understanding is zRAM is much more popularly used in embedded
systems than zswap. I seldomly(or never) hear who is using zswap
in Android. it seems pointless to force people to move to zswap, in
embedded systems we don't have a backend real block disk device
after zswap.

>