Messages in this thread | | | Date | Tue, 28 Jul 2020 13:52:31 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH v4 1/2] dma-direct: provide the ability to reserve per-numa CMA |
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On Fri, Jul 24, 2020 at 01:13:43AM +1200, Barry Song wrote: > +config CMA_PERNUMA_SIZE_MBYTES > + int "Size in Mega Bytes for per-numa CMA areas" > + depends on NUMA > + default 16 if ARM64 > + default 0 > + help > + Defines the size (in MiB) of the per-numa memory area for Contiguous > + Memory Allocator. Every numa node will get a separate CMA with this > + size. If the size of 0 is selected, per-numa CMA is disabled.
I'm still not a fan of the config option. You can just hardcode the value in CONFIG_CMDLINE based on the kernel parameter. Also I wonder if a way to expose this in the device tree might be useful, but people more familiar with the device tree and the arm code will have to chime in on that.
> struct cma *dma_contiguous_default_area; > +static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES]; > > /* > * Default global CMA area size can be defined in kernel's .config. > @@ -44,6 +51,8 @@ struct cma *dma_contiguous_default_area; > */ > static const phys_addr_t size_bytes __initconst = > (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; > +static phys_addr_t pernuma_size_bytes __initdata = > + (phys_addr_t)CMA_SIZE_PERNUMA_MBYTES * SZ_1M; > static phys_addr_t size_cmdline __initdata = -1; > static phys_addr_t base_cmdline __initdata; > static phys_addr_t limit_cmdline __initdata; > @@ -69,6 +78,13 @@ static int __init early_cma(char *p) > } > early_param("cma", early_cma); > > +static int __init early_pernuma_cma(char *p) > +{ > + pernuma_size_bytes = memparse(p, &p); > + return 0; > +} > +early_param("pernuma_cma", early_pernuma_cma); > + > #ifdef CONFIG_CMA_SIZE_PERCENTAGE > > static phys_addr_t __init __maybe_unused cma_early_percent_memory(void) > @@ -96,6 +112,33 @@ static inline __maybe_unused phys_addr_t cma_early_percent_memory(void) > > #endif > > +void __init dma_pernuma_cma_reserve(void) > +{ > + int nid; > + > + if (!pernuma_size_bytes) > + return; > + > + for_each_node_state(nid, N_MEMORY) { > + int ret; > + char name[20]; > + > + snprintf(name, sizeof(name), "pernuma%d", nid); > + ret = cma_declare_contiguous_nid(0, pernuma_size_bytes, 0, 0, > + 0, false, name, > + &dma_contiguous_pernuma_area[nid], > + nid);
This adds a > 80 char line.
> struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) > { > + int nid = dev_to_node(dev); > + > /* CMA can be used only in the context which permits sleeping */ > if (!gfpflags_allow_blocking(gfp)) > return NULL; > if (dev->cma_area) > return cma_alloc_aligned(dev->cma_area, size, gfp); > - if (size <= PAGE_SIZE || !dma_contiguous_default_area) > + if (size <= PAGE_SIZE) > return NULL; > + > + if ((nid != NUMA_NO_NODE) && !(gfp & (GFP_DMA | GFP_DMA32))) {
No need for the braces around the nid check.
> + struct cma *cma = dma_contiguous_pernuma_area[nid]; > + struct page *page; > + > + if (cma) { > + page = cma_alloc_aligned(cma, size, gfp); > + if (page) > + return page; > + } > + } > + > return cma_alloc_aligned(dma_contiguous_default_area, size, gfp);
This seems to have lost the dma_contiguous_default_area NULL check.
> + /* if dev has its own cma, free page from there */ > + if (dev->cma_area) { > + if (cma_release(dev->cma_area, page, PAGE_ALIGN(size) >> PAGE_SHIFT)) > + return;
Another overly long line.
> + } else { > + /* > + * otherwise, page is from either per-numa cma or default cma > + */ > + if (cma_release(dma_contiguous_pernuma_area[page_to_nid(page)], > + page, PAGE_ALIGN(size) >> PAGE_SHIFT)) > + return; > + > + if (cma_release(dma_contiguous_default_area, page, > + PAGE_ALIGN(size) >> PAGE_SHIFT)) > + return; > + }
I'd introduce a count variable for the value of "PAGE_ALIGN(size) >> PAGE_SHIFT" to clean al lthis up a bit.
Also please add a CONFIG_PERCPU_DMA_CMA config variable so that we don't build this code for the vast majority of users that don't need it.
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