linux-kernel - Re: [PATCH 5/6] shmem: update documentation

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Message-ID: <efae0531-7f72-a78c-07c9-82879adf5666@redhat.com>
Date:   Mon, 6 Mar 2023 15:04:57 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Luis Chamberlain <mcgrof@...nel.org>, hughd@...gle.com,
        akpm@...ux-foundation.org, willy@...radead.org, brauner@...nel.org
Cc:     linux-mm@...ck.org, p.raghav@...sung.com, da.gomez@...sung.com,
        a.manzanares@...sung.com, dave@...olabs.net, yosryahmed@...gle.com,
        keescook@...omium.org, patches@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] shmem: update documentation

On 03.03.23 00:27, Luis Chamberlain wrote:
> Update the docs to reflect a bit better why some folks prefer tmpfs
> over ramfs and clarify a bit more about the difference between brd
> ramdisks.
> 
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> ---
>   Documentation/filesystems/tmpfs.rst | 27 +++++++++++++++++++--------
>   1 file changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/filesystems/tmpfs.rst b/Documentation/filesystems/tmpfs.rst
> index 0408c245785e..e77ebdacadd0 100644
> --- a/Documentation/filesystems/tmpfs.rst
> +++ b/Documentation/filesystems/tmpfs.rst
> @@ -13,14 +13,25 @@ everything stored therein is lost.
>   
>   tmpfs puts everything into the kernel internal caches and grows and
>   shrinks to accommodate the files it contains and is able to swap
> -unneeded pages out to swap space. It has maximum size limits which can
> -be adjusted on the fly via 'mount -o remount ...'
> -
> -If you compare it to ramfs (which was the template to create tmpfs)
> -you gain swapping and limit checking. Another similar thing is the RAM
> -disk (/dev/ram*), which simulates a fixed size hard disk in physical
> -RAM, where you have to create an ordinary filesystem on top. Ramdisks
> -cannot swap and you do not have the possibility to resize them.
> +unneeded pages out to swap space.

I suppose, in contrast to ramfs, tmpfs also supports THP. Maybe worth 
adding as well.

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb