Messages in this thread | | | From | John Garry <> | Subject | Re: [PATCH v2] iommu/dma: Use NUMA aware memory allocations in __iommu_dma_alloc_pages() | Date | Tue, 20 Nov 2018 15:42:16 +0000 |
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On 20/11/2018 14:20, Robin Murphy wrote: > On 20/11/2018 13:42, John Garry wrote: >> From: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com> >> >> Change function __iommu_dma_alloc_pages() to allocate memory/pages >> for DMA from respective device NUMA node. >> >> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com> >> [JPG: Modifed to use kvzalloc() and fixed indentation] >> Signed-off-by: John Garry <john.garry@huawei.com> >> --- >> Difference v1->v2: >> - Add Ganapatrao's tag and change author >> >> This patch was originally posted by Ganapatrao in [1]. >> >> However, after initial review, it was never reposted (due to lack of >> cycles, I think). In addition, the functionality in its sibling patches >> were merged through patches, as mentioned in [2]; this also refers to a >> discussion on device local allocations vs CPU local allocations for DMA >> pool, and which is better [3]. >> >> However, as mentioned in [3], dma_alloc_coherent() uses the locality >> information from the device - as in direct DMA - so this patch is just >> applying this same policy. >> >> [1] https://lore.kernel.org/patchwork/patch/833004/ >> [2] https://lkml.org/lkml/2018/8/22/391 >> [3] >> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1692998.html >> >> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c >> index d1b0475..ada00bc 100644 >> --- a/drivers/iommu/dma-iommu.c >> +++ b/drivers/iommu/dma-iommu.c >> @@ -449,20 +449,17 @@ static void __iommu_dma_free_pages(struct page >> **pages, int count) >> kvfree(pages); >> } >> -static struct page **__iommu_dma_alloc_pages(unsigned int count, >> - unsigned long order_mask, gfp_t gfp) >> +static struct page **__iommu_dma_alloc_pages(struct device *dev, >> + unsigned int count, unsigned long order_mask, gfp_t gfp) >> { >> struct page **pages; >> - unsigned int i = 0, array_size = count * sizeof(*pages); >> + unsigned int i = 0, nid = dev_to_node(dev); >> order_mask &= (2U << MAX_ORDER) - 1; >> if (!order_mask) >> return NULL; >> - if (array_size <= PAGE_SIZE) >> - pages = kzalloc(array_size, GFP_KERNEL); >> - else >> - pages = vzalloc(array_size); >> + pages = kvzalloc_node(count * sizeof(*pages), GFP_KERNEL, nid); > > The pages array is only accessed by the CPU servicing the > iommu_dma_alloc() call, and is usually freed again before that call even > returns. It's certainly never touched by the device, so forcing it to a > potentially non-local node doesn't make a great deal of sense.
Right, it seems sensible to not make this allocation include the device-locality requirement, so can leave as is. However modifying to use kvzalloc() would seem ok.
> >> if (!pages) >> return NULL; >> @@ -483,8 +480,10 @@ static struct page >> **__iommu_dma_alloc_pages(unsigned int count, >> unsigned int order = __fls(order_mask); >> order_size = 1U << order; >> - page = alloc_pages((order_mask - order_size) ? >> - gfp | __GFP_NORETRY : gfp, order); >> + page = alloc_pages_node(nid, >> + (order_mask - order_size) ? >> + gfp | __GFP_NORETRY : gfp, >> + order); > > If we're touching this, can we sort out that horrendous ternary? FWIW I > found I have a local version of the original patch which I tweaked at > the time, and apparently I reworked this hunk as below, which does seem > somewhat nicer for the same diffstat. > > Robin. > > > @@ -446,10 +443,12 @@ static struct page > **__iommu_dma_alloc_pages(unsigned int count, > for (order_mask &= (2U << __fls(count)) - 1; > order_mask; order_mask &= ~order_size) { > unsigned int order = __fls(order_mask); > + gfp_t alloc_flags = gfp; > > order_size = 1U << order; > - page = alloc_pages((order_mask - order_size) ? > - gfp | __GFP_NORETRY : gfp, > order); > + if (order_size < order_mask) > + alloc_flags |= __GFP_NORETRY;
Sure, this can be included
> + page = alloc_pages_node(nid, alloc_flags, order); > if (!page) > continue; > if (!order) > > . >
Cheers, John
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