指令流发射和指令Cache失效是处理器能量耗散的两个重要原因.松耦合的RISC指令集所产生的程序加剧了这样的能耗,而在片上Cache有限的网络设备如路由器、交换机中,因为指令流而遭受的性能下降和功耗增加更为严重.面向网络报文转发这一重要的网络功能服务,分析了网络报文转发的指令特性,并基于RISC-V指令集架构,重定制了RV32C压缩指令扩展集.经过Spike模拟器测试,优化后压缩率缩减至70％,动态指令压缩率为90％,同时在同等Cache条件下,使用定制压缩指令的指令Cache失效率比标准RISC-V降低了30％～70％.%Instruction stream delivery and instruction Cache failure are two of the important reasons for processor energy dissipation.Programs based on loosely coupled RISC instruction sets exacerbate such energy consumption.Cache limited network devices such as routers and switches suffer more performance degradation and power consumption due to instruction related processing.This paper focuses on network packet forwarding,which is one of the most important network functions.Thought analyzing instruction characteristics of network packet forwarding,we redefine the RV32 compressed instruction extension set based on the RISC-V instruction set architecture and test it by Spike simulator.Experimental results show that the optimized compression rate is reduced to 70％ and the dynamic instruction compression rate is 90％.Meanwhile,under the same Cache conditions,our RV32C set can reduce the instruction Cache failure by 30％～70％ in comparison to the standard RISC-V set.
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