With the development of virtualization, there are more device assignment requirements. Based on VT-d interrupt remapping, Intel introduces VT-d interrupt posting as a more enhanced method to handle interrupts in the virtualization environment. The Posted Interrupts (PI) on CPU side has been already supported in Intel CPUs, with VT-d Posted Interrupt we can get some additional advantages, it can directly deliver external interrupts to running vCPUs without hypervisor involvement, decease the interrupt migration complexity, differentiate between urgent and non-urgent external interrupt, and avoid consuming host-vector for each interrupt to vCPU. In this presentation, Feng will talk about the mechanism of VT-d PI and its advantages, as well as some performance data of I/O intensive workload in Xen, which will show the performance gain after using VT-d PI.
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