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Date:   Fri, 12 Aug 2022 18:11:32 -0700
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Subject: Re: [RFC PATCH v2 09/12] mm: Make MAX_ORDER of buddy allocator
 configurable via Kconfig SET_MAX_ORDER.
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To:     Zi Yan <ziy@nvidia.com>, linux-mm@kvack.org
Cc:     David Hildenbrand <david@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Yang Shi <shy828301@gmail.com>,
        David Rientjes <rientjes@google.com>,
        James Houghton <jthoughton@google.com>,
        Mike Rapoport <rppt@kernel.org>, linux-kernel@vger.kernel.org
References: <20220811231643.1012912-1-zi.yan@sent.com>
 <20220811231643.1012912-10-zi.yan@sent.com>
From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <20220811231643.1012912-10-zi.yan@sent.com>
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Hi--

On 8/11/22 16:16, Zi Yan wrote:

> diff --git a/mm/Kconfig b/mm/Kconfig
> index bbe31e85afee..e558f5679707 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -441,6 +441,20 @@ config SPARSEMEM_VMEMMAP
>  	  pfn_to_page and page_to_pfn operations.  This is the most
>  	  efficient option when sufficient kernel resources are available.
>  
> +config SET_MAX_ORDER
> +	int "Set maximum order of buddy allocator"
> +    depends on SPARSEMEM_VMEMMAP && (ARCH_FORCE_MAX_ORDER = 0)
> +	range 10 255
> +	default "10"
> +	help
> +	  The kernel memory allocator divides physically contiguous memory
> +	  blocks into "zones", where each zone is a power of two number of
> +	  pages.  This option selects the largest power of two that the kernel
> +	  keeps in the memory allocator.  If you need to allocate very large
> +	  blocks of physically contiguous memory, then you may need to
> +	  increase this value. A value of 10 means that the largest free memory
> +	  block is 2^10 pages.

Please make sure that all lines of help text are indented with one tab + 2 spaces,
as specified in Documentation/process/coding-style.rst.

thanks.
-- 
~Randy