On Sun, Jun 28, 2020 at 11:12:50PM +1200, Barry Song wrote: > This is useful for at least two scenarios: > 1. ARM64 smmu will get memory from local numa node, it can save its > command queues and page tables locally. Tests show it can decrease > dma_unmap latency at lot. For example, without this patch, smmu on > node2 will get memory from node0 by calling dma_alloc_coherent(), > typically, it has to wait for more than 560ns for the completion of > CMD_SYNC in an empty command queue; with this patch, it needs 240ns > only. > 2. when we set iommu passthrough, drivers will get memory from CMA, > local memory means much less latency.
I really don't like the config options. With the boot parameters you can always hardcode that in CONFIG_CMDLINE anyway. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
