Optimization Of Virtual Machine Based On GODSON CPU

The Godson series of CPU are the first self-designed high performance, general-purposed microprocessors in China, which implement MIPS64 instruction set and several special instructions. It achieves high performance even under low frequency by using advanced architecture design, and has become one of the advanced superscalar processors in the world. At present, the most popular architecture of service machine is X86, most desktop applications and applied software are based on X86, but the Godson CPU is base on MIPS. In order to run applications of service machine on Godson CPU, it is the major task to be compatible with the X86 architecture; also, there are more and more varieties of applications based on X86 architecture, many business software are based on X86 architecture, in order to run varieties of applications, it needs to be compatible with X86 architecture.At present, there are many virtual machines of open source, which can implement the translation from MIPS to X86. QEMU virtual machine is one of them, which has two working modes: system and process, and it can transform many platforms from one to another. there are many merits of multi-platforms, high efficiency of translation, open sources and so on, so we choice the QEMU as the processing virtual machine on the Godson CPU, to attain the aims of being compatible with X86 applications.Because of the translation only based on the software, the running speed of the programs has become the key element. So implementing the virtual machine only based on software is hard to satisfy people, it is the key mask to accelerate the virtual machine. There have being many hardware supports to improve the performance of the virtual machine in the specifications of the Godson III, but the optimization of the software is also important. This paper describes the optimization of the QEMU software. The optimization contains four aspects: the mapping of registers, no-align accessing memory and MMX instructions. On the platform of Godson 2F and Godson 3 FPGA, with the SPEC2000, the experiment results show that we get 19. 94% improvement on SPEC2000INT and 53.44% improvement on SPEC2000FP.