Research Of IRQ Load Balancing For SMP Virtual Machines

Virtualization technology which provides server consolidation and security isolationhas already been widely used in industry. Though the split driver model solves theproblem that how multiple virtual machines share single one physical device, all virtualinterrupts are all delivered to the first virtual processor of driver domains. This staticdistribution method results in servious virtual interrupt load imbalance. Then it increasesthe delay of interrupt process.The IRQ load balancing for SMP virtual machines effectively solved the aboveproblem. Aimed at the imbalance of virtual interrupts load and the large delay of virtualinterrupts process, our methodology distribute all virtual interrupts to all available virtualprocessors according to their priority. This method consists of three main mechanisms.The first one is that through evenly delivering the virtual interrupts to all virtualprocessors it can allows all virtual processor can participate in handling virtual interrupts.This mechanism balances the virtual interrupts load among all available virtual processors.The second one is that by sampling on virtual interrupt load and adjusting the threshold itcan find the best performance under various virtual interrupt loads. This mechanism adjustthe virtual interrupts decentralize through sampling on the virtual interrupts load andadjusting the threshold. The last one is adjusting virtual interrupt deliver by hypervisorscheduler state to decrease the delay of virtual interrupt handling. This mechanismconsiders the virtual processors running state when deliver virtual interrupts to decreasethe delay of virtual interrupts process. Through all these mechanism, the virtual interruptsdynmiac deliver methodology can balance the virtual interrupts load and decrease thedelay of virtual interrupts processing.Experiments show that when use the interrupts load balancing methodology, thenetwork receiving performance can be improved by99%when the packet size is52byteand by16%when the packet size is512byte, also the performance of concureent webserver can be improved by4%.