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The IOMMU allows the OS to encapsulate I/O devices in their own virtual memory spaces, thus restricting their DMAs to specific memory pages. The OS uses the IOMMU to protect itself against buggy drivers and malicious/errant devices. But the added protection comes at a cost, degrading the throughput of I/O-intensive workloads by up to an order of magnitude.(More)
Operating systems can defend themselves against misbehaving I/O devices and drivers by employing intra-OS protection. With “strict” intra-OS protection, the OS uses the IOMMU to map each DMA buffer immediately before the DMA occurs and to unmap it immediately after. Strict protection is costly due to IOMMU-related hardware overheads, motivating “deferred”(More)
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