linux-kernel - Re: [PATCH v3] docs: update THP admin guide about non-tmpfs filesystem support

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Message-ID: <spuuu4rg3awuakis2qepqob33nj6ex2w2p7u4jbdv4fhvicnxe@dcec3e3eaz53>
Date: Tue, 8 Apr 2025 11:44:22 +0200
From: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
To: David Hildenbrand <david@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, 
	Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org, willy@...radead.org, 
	linux-mm@...ck.org, Bagas Sanjaya <bagasdotme@...il.com>, da.gomez@...nel.org, 
	mcgrof@...nel.org, gost.dev@...sung.com, linux-doc@...r.kernel.org, 
	Pankaj Raghav <p.raghav@...sung.com>
Subject: Re: [PATCH v3] docs: update THP admin guide about non-tmpfs
 filesystem support

On Fri, Apr 04, 2025 at 09:16:10PM +0200, David Hildenbrand wrote:
> On 04.04.25 16:06, Pankaj Raghav (Samsung) wrote:
> > From: Pankaj Raghav <p.raghav@...sung.com>
> > 
> > THP support for non-tmpfs filesystem has been around for some time now.
> > Update the admin guide to reflect it.
> > 
> > While we are at it, move FilePmdMapped to previous paragraph for clarity,
> > and clarify ShmemPmdMapped & ShmemHugePage.
> > 
> > Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> > Acked-by: David Hildenbrand <david@...hat.com>
> > ---
> 
> BTW, we should go over the whole document and bring it up to date.
> Interestingly, it starts with
> 
> "Performance critical computing applications dealing with large memory
> working sets are already running on top of libhugetlbfs and in turn
> hugetlbfs. Transparent HugePage Support (THP) is an alternative mean of
> using huge pages for the backing of virtual memory with huge pages
> that supports the automatic promotion and demotion of page sizes and
> without the shortcomings of hugetlbfs.
> 
> Currently THP only works for anonymous memory mappings and tmpfs/shmem.
> But in the future it can expand to other filesystems."

As a part of this patch, I do change 2nd paragraph:

-Currently THP only works for anonymous memory mappings and tmpfs/shmem.
-But in the future it can expand to other filesystems.
+Currently, THP only works for anonymous memory mappings, tmpfs/shmem and
+filesystems that support large folios.

Do we need to add more changes to the first paragraph as well?

--
Pankaj