Re: [PATCH 27/33] dma-direct: use node local allocations for coherent memory

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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.
--
To unsubscribe from this list: send the line "unsubscribe linux-parisc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux SoC]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux