Messages in this thread | | | Date | Fri, 21 Aug 2020 10:01:16 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v6 2/2] arm64: mm: reserve per-numa CMA to localize coherent dma buffers |
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On Fri, Aug 21, 2020 at 02:26:15PM +1200, Barry Song wrote: > Right now, smmu is using dma_alloc_coherent() to get memory to save queues > and tables. Typically, on ARM64 server, there is a default CMA located at > node0, which could be far away from node2, node3 etc. > with this patch, smmu will get memory from local numa node to save command > queues and page tables. that means dma_unmap latency will be shrunk much. > Meanwhile, when iommu.passthrough is on, device drivers which call dma_ > alloc_coherent() will also get local memory and avoid the travel between > numa nodes. > > Cc: Christoph Hellwig <hch@lst.de> > Cc: Marek Szyprowski <m.szyprowski@samsung.com> > Cc: Will Deacon <will@kernel.org> > Cc: Robin Murphy <robin.murphy@arm.com> > Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> > Cc: Steve Capper <steve.capper@arm.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Mike Rapoport <rppt@linux.ibm.com> > Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> > --- > -v6: rebase on top of 5.9-rc1 > > arch/arm64/mm/init.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 481d22c32a2e..f1c75957ff3c 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -429,6 +429,8 @@ void __init bootmem_init(void) > arm64_hugetlb_cma_reserve(); > #endif > > + dma_pernuma_cma_reserve();
I think will have to do for now, but I still wish that more of this was driven from the core code so that we don't have to worry about initialisation order and whether things are early/late enough on a per-arch basis.
Acked-by: Will Deacon <will@kernel.org>
Will
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