| 摘要 |
The present invention provides a machine system that enables the arbitration of IO accesses and band control based on the priority of virtual servers while curbing performance overhead during IO sharing among the virtual servers. A virtual machine system including a CPU, a memory, and an IO interface includes a hypervisor that generates plural virtual servers, and an IO controller that controls the IO interface. The IO controller includes: a DMA receiving unit that receives DMA requests from the IO interface; a decoder that decodes received DMA requests and locates the corresponding virtual servers; a DMA monitoring counter that monitors DMA processing status for each of the virtual servers; a threshold register set in advance for each of the virtual servers; and a priority deciding unit that compares the DMA monitoring counter and the value of the threshold register, and based on processing priority obtained as a result of the comparison, decides the priority of processing of the received DMA requests.
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