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.
