linux-kernel - Re: [PATCH 3/6] mm: hugetlb_vmemmap: introduce the name HVO

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Message-ID: <4a6023f3-0fbd-32cf-7e52-bc72e2b4a407@redhat.com>
Date:   Mon, 13 Jun 2022 17:39:59 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Muchun Song <songmuchun@...edance.com>, mike.kravetz@...cle.com,
        akpm@...ux-foundation.org, corbet@....net
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH 3/6] mm: hugetlb_vmemmap: introduce the name HVO

On 13.06.22 08:35, Muchun Song wrote:
> It it inconvenient to mention the feature of optimizing vmemmap pages associated
> with HugeTLB pages when communicating with others since there is no specific or
> abbreviated name for it when it is first introduced.  Let us give it a name HVO
> (HugeTLB Vmemmap Optimization) from now.
> 
> This commit also updates the document about "hugetlb_free_vmemmap" by the way
> discussed in thread [1].
> 
> Link: https://lore.kernel.org/all/21aae898-d54d-cc4b-a11f-1bb7fddcfffa@redhat.com/ [1]
> Signed-off-by: Muchun Song <songmuchun@...edance.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt |  7 ++++---
>  Documentation/admin-guide/mm/hugetlbpage.rst    |  3 +--
>  Documentation/admin-guide/sysctl/vm.rst         |  3 +--
>  fs/Kconfig                                      | 13 ++++++-------
>  mm/hugetlb_vmemmap.c                            |  8 ++++----
>  mm/hugetlb_vmemmap.h                            |  4 ++--
>  6 files changed, 18 insertions(+), 20 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 391b43fee93e..7539553b3fb0 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1725,12 +1725,13 @@
>  	hugetlb_free_vmemmap=
>  			[KNL] Reguires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
>  			enabled.
> +			Control if HugeTLB Vmemmap Optimization (HVO) is enabled.
>  			Allows heavy hugetlb users to free up some more
>  			memory (7 * PAGE_SIZE for each 2MB hugetlb page).
> -			Format: { [oO][Nn]/Y/y/1 | [oO][Ff]/N/n/0 (default) }
> +			Format: { on | off (default) }
>  
> -			[oO][Nn]/Y/y/1: enable the feature
> -			[oO][Ff]/N/n/0: disable the feature
> +			on: enable HVO
> +			off: disable HVO
>  
>  			Built with CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=y,
>  			the default is on.
> diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst
> index a90330d0a837..64e0d5c512e7 100644
> --- a/Documentation/admin-guide/mm/hugetlbpage.rst
> +++ b/Documentation/admin-guide/mm/hugetlbpage.rst
> @@ -164,8 +164,7 @@ default_hugepagesz
>  	will all result in 256 2M huge pages being allocated.  Valid default
>  	huge page size is architecture dependent.
>  hugetlb_free_vmemmap
> -	When CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is set, this enables optimizing
> -	unused vmemmap pages associated with each HugeTLB page.
> +	When CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is set, this enables HVO.

Heh, it would be convenient to call this

CONFIG_HUGETLB_PAGE_VMEMMAP_OPTIMIZATION (HVO) then.

-- 
Thanks,

David / dhildenb