[bug report] iommu_dma_unmap_sg() is very slow then running IO from remote numa node

[Russell King (Oracle)]

On Fri, Jul 09, 2021 at 04:38:09PM +0800, Ming Lei wrote:
> I observed that NVMe performance is very bad when running fio on one
> CPU(aarch64) in remote numa node compared with the nvme pci numa node.

Have you checked the effect of running a memory-heavy process using
memory from node 1 while being executed by CPUs in node 0?

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