linux-kernel - Re: [RFC PATCH 5/9] mm: zswap: remove zswap_same_filled_pages

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Date: Thu, 28 Mar 2024 19:14:25 -0700
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Johannes Weiner <hannes@...xchg.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Nhat Pham <nphamcs@...il.com>, 
	Chengming Zhou <chengming.zhou@...ux.dev>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	"Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
Subject: Re: [RFC PATCH 5/9] mm: zswap: remove zswap_same_filled_pages_enabled

On Thu, Mar 28, 2024 at 1:06 PM Yosry Ahmed <yosryahmed@...gle.com> wrote:
>
> On Thu, Mar 28, 2024 at 12:11 PM Johannes Weiner <hannes@...xchg.org> wrote:
> >
> > On Mon, Mar 25, 2024 at 11:50:13PM +0000, Yosry Ahmed wrote:
> > > There is no logical reason to refuse storing same-filled pages more
> > > efficiently and opt for compression. Remove the userspace knob.
> > >
> > > Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
> >
> > Acked-by: Johannes Weiner <hannes@...xchg.org>
> >
> > I also think the non_same_filled_pages_enabled option should go
> > away. Both of these tunables are pretty bizarre.
>
> Happy to remove both in the next version :)

I thought non_same_filled_pages_enabled was introduced with the
initial support for same-filled pages, but it was introduced
separately (and much more recently):
https://lore.kernel.org/all/7dbafa963e8bab43608189abbe2067f4b9287831.1641247624.git.maciej.szmigiero@oracle.com/

I am CCing Maciej to hear more about the use case for this.

>
> Thanks!