On 10/01/18 15:30, Christoph Hellwig wrote:
On Wed, Jan 10, 2018 at 12:06:22PM +0000, Robin Murphy wrote:
On 10/01/18 08:00, Christoph Hellwig wrote:
To preserve the x86 behavior.
And combined with patch 10/22 of the SWIOTLB refactoring, this means
SWIOTLB allocations will also end up NUMA-aware, right? Great, that's what
we want on arm64 too :)
Well, only for swiotlb allocations that can be satisfied by
dma_direct_alloc. If we actually have to fall back to the swiotlb
buffers there is not node affinity yet.
Yeah, when I looked into it I reached the conclusion that per-node
bounce buffers probably weren't worth it - if you have to bounce you've
already pretty much lost the performance game, and if the CPU doing the
bouncing happens to be on a different node from the device you've
certainly lost either way. Per-node CMA zones we definitely *would*
like, but that's a future problem (it looks technically feasible without
huge infrastructure changes, but fiddly).
Robin.
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