On Fri, Aug 21, 2020 at 02:26:14PM +1200, Barry Song wrote:
> 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]
> + [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.
What is the default behaviour if this option is not specified? Seems like
that should be mentioned here.
> diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
> index 847a9d1fa634..db7a37ed35eb 100644
> --- a/kernel/dma/Kconfig
> +++ b/kernel/dma/Kconfig
> @@ -118,6 +118,16 @@ config DMA_CMA
> If unsure, say "n".
>
> if DMA_CMA
> +
> +config DMA_PERNUMA_CMA
> + bool "Enable separate DMA Contiguous Memory Area for each NUMA Node"
I don't understand the need for this config option. If you have DMA_DMA and
you have NUMA, why wouldn't you want this enabled?
> + help
> + Enable this option to get pernuma CMA areas so that devices like
> + ARM64 SMMU can get local memory by DMA coherent APIs.
> +
> + You can set the size of pernuma CMA by specifying "pernuma_cma=size"
> + on the kernel's command line.
> +
> comment "Default contiguous memory area size:"
>
> config CMA_SIZE_MBYTES
> 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;
> +
> +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;
If this is useful (I assume it is), then I think we should have a non-zero
default value, a bit like normal CMA does via CMA_SIZE_MBYTES.
> + for_each_node_state(nid, N_ONLINE) {
for_each_online_node() {
> + int ret;
> + char name[20];
20?
Ah, wait, this is copy-pasta from hugetlb_cma_reserve(). Can you factor out
the common parts at all?
Will
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