linux-kernel - Re: [PATCH v6 1/2] dma-contiguous: provide the ability to reserve per-numa CMA

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Message-ID: <5dbe456d-d408-11ef-788e-63d996435fa8@infradead.org>
Date:   Thu, 20 Aug 2020 19:49:54 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Barry Song <song.bao.hua@...ilicon.com>, hch@....de,
        m.szyprowski@...sung.com, robin.murphy@....com, will@...nel.org,
        ganapatrao.kulkarni@...ium.com, catalin.marinas@....com
Cc:     iommu@...ts.linux-foundation.org, linuxarm@...wei.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        huangdaode@...wei.com,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Steve Capper <steve.capper@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.ibm.com>
Subject: Re: [PATCH v6 1/2] dma-contiguous: provide the ability to reserve
 per-numa CMA

On 8/20/20 7:26 PM, Barry Song wrote:
> 
> 
> Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Cc: Christoph Hellwig <hch@....de>
> Cc: Marek Szyprowski <m.szyprowski@...sung.com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Robin Murphy <robin.murphy@....com>
> Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> Cc: Steve Capper <steve.capper@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Mike Rapoport <rppt@...ux.ibm.com>
> Signed-off-by: Barry Song <song.bao.hua@...ilicon.com>
> ---
>  v6: rebase on top of 5.9-rc1;
>      doc cleanup
> 
>  .../admin-guide/kernel-parameters.txt         |   9 ++
>  include/linux/dma-contiguous.h                |   6 ++
>  kernel/dma/Kconfig                            |  10 ++
>  kernel/dma/contiguous.c                       | 100 ++++++++++++++++--
>  4 files changed, 115 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index bdc1f33fd3d1..3f33b89aeab5 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -599,6 +599,15 @@
>  			altogether. For more information, see
>  			include/linux/dma-contiguous.h
>  
> +	pernuma_cma=nn[MG]

memparse() allows any one of these suffixes: K, M, G, T, P, E
and nothing in the option parsing function cares what suffix is used...

> +			[ARM64,KNL]
> +			Sets the size of kernel per-numa memory area for
> +			contiguous memory allocations. A value of 0 disables
> +			per-numa CMA altogether. 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.
> +
>  	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

> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index cff7e60968b9..89b95f10e56d 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -69,6 +69,19 @@ static int __init early_cma(char *p)
>  }
>  early_param("cma", early_cma);
>  
> +#ifdef CONFIG_DMA_PERNUMA_CMA
> +
> +static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES];
> +static phys_addr_t pernuma_size_bytes __initdata;

why phys_addr_t? couldn't it just be unsigned long long?

OK, so cma_declare_contiguous_nid() uses phys_addr_t. Fine.

> +
> +static int __init early_pernuma_cma(char *p)
> +{
> +	pernuma_size_bytes = memparse(p, &p);
> +	return 0;
> +}
> +early_param("pernuma_cma", early_pernuma_cma);
> +#endif
> +
>  #ifdef CONFIG_CMA_SIZE_PERCENTAGE
>  
>  static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
> @@ -96,6 +109,34 @@ static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
>  
>  #endif
>  
> +#ifdef CONFIG_DMA_PERNUMA_CMA
> +void __init dma_pernuma_cma_reserve(void)
> +{
> +	int nid;
> +
> +	if (!pernuma_size_bytes)
> +		return;
> +
> +	for_each_node_state(nid, N_ONLINE) {
> +		int ret;
> +		char name[20];
> +		struct cma **cma = &dma_contiguous_pernuma_area[nid];
> +
> +		snprintf(name, sizeof(name), "pernuma%d", nid);
> +		ret = cma_declare_contiguous_nid(0, pernuma_size_bytes, 0, 0,
> +						 0, false, name, cma, nid);
> +		if (ret) {
> +			pr_warn("%s: reservation failed: err %d, node %d", __func__,
> +				ret, nid);
> +			continue;
> +		}
> +
> +		pr_debug("%s: reserved %llu MiB on node %d\n", __func__,
> +			(unsigned long long)pernuma_size_bytes / SZ_1M, nid);

Conversely, if you want to leave pernuma_size_bytes as phys_addr_t,
you should use %pa (or %pap) to print it.

> +	}
> +}
> +#endif



-- 
~Randy