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Subject: Re: [PATCH v7 1/3] dma-contiguous: provide the ability to reserve
 per-numa CMA
To:     Barry Song <song.bao.hua@hisilicon.com>, hch@lst.de,
        m.szyprowski@samsung.com, robin.murphy@arm.com, will@kernel.org,
        ganapatrao.kulkarni@cavium.com, catalin.marinas@arm.com,
        akpm@linux-foundation.org
Cc:     iommu@lists.linux-foundation.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        prime.zeng@hisilicon.com, huangdaode@huawei.com,
        linuxarm@huawei.com,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        Steve Capper <steve.capper@arm.com>,
        Mike Rapoport <rppt@linux.ibm.com>
References: <20200821113355.6140-1-song.bao.hua@hisilicon.com>
 <20200821113355.6140-2-song.bao.hua@hisilicon.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <5eafce91-cc92-e6ed-23b0-98f253129e1b@infradead.org>
Date:   Fri, 21 Aug 2020 09:08:27 -0700
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On 8/21/20 4:33 AM, Barry Song wrote:
> ---
>  -v7: with respect to Will's comments
>  * move to use for_each_online_node
>  * add description if users don't specify pernuma_cma
>  * provide default value for CONFIG_DMA_PERNUMA_CMA
> 
>  .../admin-guide/kernel-parameters.txt         |  11 ++
>  include/linux/dma-contiguous.h                |   6 ++
>  kernel/dma/Kconfig                            |  11 ++
>  kernel/dma/contiguous.c                       | 100 ++++++++++++++++--
>  4 files changed, 118 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index bdc1f33fd3d1..c609527fc35a 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -599,6 +599,17 @@
>  			altogether. For more information, see
>  			include/linux/dma-contiguous.h
>  
> +	pernuma_cma=nn[MG]
> +			[ARM64,KNL]
> +			Sets the size of kernel per-numa memory area for
> +			contiguous memory allocations. A value of 0 disables
> +			per-numa CMA altogether. And If this option is not
> +			specificed, the default value is 0.
> +			With per-numa CMA enabled, DMA users on node nid will
> +			first try to allocate buffer from the pernuma area
> +			which is located in node nid, if the allocation fails,
> +			they will fallback to the global default memory area.
> +

Entries in kernel-parameters.txt are supposed to be in alphabetical order
but this one is not.  If you want to keep it near the cma= entry, you can
rename it like Mike suggested.  Otherwise it needs to be moved.


>  	cmo_free_hint=	[PPC] Format: { yes | no }
>  			Specify whether pages are marked as being inactive
>  			when they are freed.  This is used in CMO environments


-- 
~Randy