From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, linux-mm@kvack.org,
Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Will.Deacon@arm.com, lorenzo.pieralisi@arm.com,
hanjun.guo@linaro.org, joro@8bytes.org, vbabka@suse.cz,
akpm@linux-foundation.org, mhocko@suse.com,
Tomasz.Nowicki@cavium.com, Robert.Richter@cavium.com,
jnair@caviumnetworks.com, gklkml16@gmail.com
Subject: Re: [PATCH 3/4] iommu/arm-smmu-v3: Use NUMA memory allocations for stream tables and comamnd queues
Date: Thu, 21 Sep 2017 16:26:39 +0200 [thread overview]
Message-ID: <20170921142639.GA18211@lst.de> (raw)
In-Reply-To: <db28d6ff-77e5-ed59-c1b8-57c917564a68@arm.com>
On Thu, Sep 21, 2017 at 12:58:04PM +0100, Robin Murphy wrote:
> Christoph, Marek; how reasonable do you think it is to expect
> dma_alloc_coherent() to be inherently NUMA-aware on NUMA-capable
> systems? SWIOTLB looks fairly straightforward to fix up (for the simple
> allocation case; I'm not sure it's even worth it for bounce-buffering),
> but the likes of CMA might be a little trickier...
I think allocating data node local to dev is a good default. I'm not
sure if we'd still need a version that takes an explicit node, though.
On the one hand devices like NVMe or RDMA nics have queues that are
assigned to specific cpus and thus have an inherent affinity to given
nodes. On the other hand we'd still need to access the PCIe device,
so for it to make sense we'd need to access the dma memory a lot more
from the host than from the device, and I'm not sure if we ever have
devices where that is the case (which would not be optimal to start
with).
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next prev parent reply other threads:[~2017-09-21 14:26 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-21 8:59 [PATCH 0/4] numa, iommu/smmu: IOMMU/SMMU driver optimization for NUMA systems Ganapatrao Kulkarni
2017-09-21 8:59 ` [PATCH 1/4] mm: move function alloc_pages_exact_nid out of __meminit Ganapatrao Kulkarni
2017-09-26 13:35 ` Michal Hocko
2017-09-21 8:59 ` [PATCH 2/4] numa, iommu/io-pgtable-arm: Use NUMA aware memory allocation for smmu translation tables Ganapatrao Kulkarni
2017-09-21 11:11 ` Robin Murphy
2017-09-22 15:33 ` Ganapatrao Kulkarni
2017-09-21 8:59 ` [PATCH 3/4] iommu/arm-smmu-v3: Use NUMA memory allocations for stream tables and comamnd queues Ganapatrao Kulkarni
2017-09-21 11:58 ` Robin Murphy
2017-09-21 14:26 ` Christoph Hellwig [this message]
2017-09-29 12:13 ` Marek Szyprowski
2017-10-04 13:53 ` Ganapatrao Kulkarni
2017-10-18 13:36 ` Robin Murphy
2017-11-06 9:04 ` Ganapatrao Kulkarni
2017-09-21 8:59 ` [PATCH 4/4] iommu/dma, numa: Use NUMA aware memory allocations in __iommu_dma_alloc_pages Ganapatrao Kulkarni
2017-09-21 11:41 ` Robin Murphy
2017-09-22 15:44 ` Ganapatrao Kulkarni
2017-10-18 13:28 ` [PATCH 0/4] numa, iommu/smmu: IOMMU/SMMU driver optimization for NUMA systems Will Deacon
2018-08-22 13:44 ` John Garry
2018-08-22 14:56 ` Robin Murphy
2018-08-22 16:07 ` John Garry
2018-08-22 17:57 ` Ganapatrao Kulkarni
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