linux-kernel - Re: [PATCH v2 1/1] mm/madvise: add MADV_F_COLLAPSE_LIGHT to process

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Date: Fri, 26 Jan 2024 20:52:12 +0800
From: Lance Yang <ioworker0@...il.com>
To: akpm@...ux-foundation.org, Michal Hocko <mhocko@...e.com>, 
	"Zach O'Keefe" <zokeefe@...gle.com>, Yang Shi <shy828301@...il.com>, 
	David Hildenbrand <david@...hat.com>
Cc: songmuchun@...edance.com, peterx@...hat.com, mknyszek@...gle.com, 
	minchan@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	linux-api@...r.kernel.org
Subject: Re: [PATCH v2 1/1] mm/madvise: add MADV_F_COLLAPSE_LIGHT to process_madvise()

On Fri, Jan 26, 2024 at 6:15 PM Lance Yang <ioworker0@...il.com> wrote:
[...]
> > If the kernel supports a more relaxed (opportunistic)
> > MADV_COLLAPSE, we will modify the THP settings as follows:
> >
> > echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
> > echo madvise >/sys/kernel/mm/transparent_hugepage/defrag
>
> The correct THP settings should be:
> echo always >/sys/kernel/mm/transparent_hugepage/enabled
> echo madvise >/sys/kernel/mm/transparent_hugepage/defrag
>

Apologize for the confusion in my previous email.

The third type of requirements prefers not to use huge pages at all.
The correct THP settings should be:
echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
echo defer+madvise >/sys/kernel/mm/transparent_hugepage/defrag

> >
> > Then, we will use process_madvise(MADV_COLLAPSE, xx_relaxed_flag)
> > to address the requirements of the second type.
[...]