​IOMMU in Virtualized Environments

The Input-Output Memory Management Unit (IOMMU) feature of the processor prevents I/O devices from accessing memory outside the boundaries set by the OS. It also allows devices to be directly assigned to a Virtual Machine. However, IOMMU can affect performance, both in latency (each DMA access by the device must be translated by the IOMMU), and in CPU utilization (each buffer assigned to every device must be mapped in the IOMMU).

If you experience significant performance issues with IOMMU, try adding the following commands to the kernel boot command line: