linux-kernel - Re: [RFC PATCH 0/2] SKSM: Synchronous Kernel Samepage Merging

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Message-ID: <CAHk-=wi5-+P49c3NPeZB_qrNyOtAJS3YadHB0q7J3eZ3UUwrjw@mail.gmail.com>
Date: Thu, 27 Feb 2025 21:17:47 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org, 
	Matthew Wilcox <willy@...radead.org>, Olivier Dion <odion@...icios.com>, linux-mm@...ck.org
Subject: Re: [RFC PATCH 0/2] SKSM: Synchronous Kernel Samepage Merging

On Thu, 27 Feb 2025 at 19:03, Mathieu Desnoyers
<mathieu.desnoyers@...icios.com> wrote:
>
> I'd be fine with SKSM replacing KSM entirely. However, I don't
> think we should try to re-implement the existing KSM userspace ABIs
> over SKSM.

No, absolutely. The only point (for me) for your new synchronous one
would be if it replaced the kernel thread async scanning, which would
make the old user space interface basically pointless.

But I don't actually know who uses KSM right now. My reaction really
comes from a "it's not nice code in the kernel", not from any actual
knowledge of the users.

Maybe it works really well in some cloud VM environment, and we're
stuck with it forever.

In which case I don't want to see some second different interface that
just makes it all worse.

                 Linus