ELI: Bare-Metal Performance for I/O Virtualization
Direct device assignment enhances the performance of guest virtual machines by allowing them to communicate with I/O devices without host involvement. But even with device assignment, guests are still unable to approach bare-metal performance, because the host intercepts all interrupts, including those interrupts generated by assigned devices to signal to guests the completion of their I/O requests. The host involvement induces multiple unwarranted guest/host context switches, which significantly hamper the performance of I/O intensive workloads. To solve this problem, the authors present ELI (Exit-Less Interrupts), a software-only approach for handling interrupts within guest virtual machines directly and securely.