From: Christoph Hellwig <hch@lst.de>
To: Barry Song <song.bao.hua@hisilicon.com>
Cc: catalin.marinas@arm.com, Steve Capper <steve.capper@arm.com>,
robin.murphy@arm.com, linuxarm@huawei.com,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
ganapatrao.kulkarni@cavium.com,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@linux.ibm.com>,
will@kernel.org, hch@lst.de,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/2] dma-direct: provide the ability to reserve per-numa CMA
Date: Wed, 22 Jul 2020 16:29:43 +0200 [thread overview]
Message-ID: <20200722142943.GB17658@lst.de> (raw)
In-Reply-To: <20200628111251.19108-2-song.bao.hua@hisilicon.com>
On Sun, Jun 28, 2020 at 11:12:50PM +1200, Barry Song wrote:
> struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
> {
> size_t count = size >> PAGE_SHIFT;
> struct page *page = NULL;
> struct cma *cma = NULL;
> + int nid = dev ? dev_to_node(dev) : NUMA_NO_NODE;
> + bool alloc_from_pernuma = false;
> +
> + if ((count <= 1) && !(dev && dev->cma_area))
> + return NULL;
>
> if (dev && dev->cma_area)
> cma = dev->cma_area;
> - else if (count > 1)
> + else if ((nid != NUMA_NO_NODE) && dma_contiguous_pernuma_area[nid]
> + && !(gfp & (GFP_DMA | GFP_DMA32))) {
> + cma = dma_contiguous_pernuma_area[nid];
> + alloc_from_pernuma = true;
> + } else {
> cma = dma_contiguous_default_area;
> + }
I find the function rather confusing now. What about something
like (this relies on the fact that dev should never be NULL in the
DMA API)
struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
{
size_t cma_align = min_t(size_t, get_order(size), CONFIG_CMA_ALIGNMENT);
size_t count = size >> PAGE_SHIFT;
if (gfpflags_allow_blocking(gfp))
return NULL;
gfp &= __GFP_NOWARN;
if (dev->cma_area)
return cma_alloc(dev->cma_area, count, cma_align, gfp);
if (count <= 1)
return NULL;
if (IS_ENABLED(CONFIG_PERNODE_CMA) && !(gfp & (GFP_DMA | GFP_DMA32)) {
int nid = dev_to_node(dev);
struct cma *cma = dma_contiguous_pernuma_area[nid];
struct page *page;
if (cma) {
page = cma_alloc(cma, count, cma_align, gfp);
if (page)
return page;
}
}
return cma_alloc(dma_contiguous_default_area, count, cma_align, gfp);
}
> + /*
> + * otherwise, page is from either per-numa cma or default cma
> + */
> + int nid = page_to_nid(page);
> +
> + if (nid != NUMA_NO_NODE) {
> + if (cma_release(dma_contiguous_pernuma_area[nid], page,
> + PAGE_ALIGN(size) >> PAGE_SHIFT))
> + return;
> + }
> +
> + if (cma_release(dma_contiguous_default_area, page,
How can page_to_nid ever return NUMA_NO_NODE?
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next prev parent reply other threads:[~2020-07-22 14:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-28 11:12 [PATCH v3 0/2] make dma_alloc_coherent NUMA-aware by per-NUMA CMA Barry Song
2020-06-28 11:12 ` [PATCH v3 1/2] dma-direct: provide the ability to reserve per-numa CMA Barry Song
2020-07-22 14:16 ` Christoph Hellwig
2020-07-22 21:26 ` Song Bao Hua (Barry Song)
2020-07-23 11:55 ` Christoph Hellwig
2020-07-22 14:29 ` Christoph Hellwig [this message]
2020-07-22 21:41 ` Song Bao Hua (Barry Song)
2020-07-23 12:00 ` Christoph Hellwig
2020-07-23 12:08 ` Song Bao Hua (Barry Song)
2020-06-28 11:12 ` [PATCH v3 2/2] arm64: mm: reserve per-numa CMA to localize coherent dma buffers Barry Song
2020-07-13 2:45 ` [PATCH v3 0/2] make dma_alloc_coherent NUMA-aware by per-NUMA CMA Song Bao Hua (Barry Song)
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