同时多线程结构的线程预构

Simultaneous Multi-Threading Architecture Using Novel Thread Pre-Construction Concept

同时多线程结构中,多个线程共享一个取指单元。要选择最合适的取指线程,需要在调度策略里综合考虑流水线反馈条件或者预测流水线行为,这是非常困难的。提出了线程预构的概念,把线程取指调度分解为线程预构调度和就绪线程取指调度,分别解决错误路径取指问题和指令队列阻塞问题。提出了线程缓冲的链表结构,实现了线程预构的概念,与国际公认的基准SMT结构相比,IPC平均提高9.39%。

Simultaneous Multi-Threading （SMT）, which allows multiple threads to share all the processor＇s resources every cycle, can exploit both the instruction level parallelism and thread levelparallelism. Instruction fetch policy is important for acquiring higher performance. To choose the most appropriate thread from all active threads, the thread fetch schedule policy must take into account the feedbacks and also the predicted behavior of different pipeline stages. As the fetch schedule mechanism is very complex, its implementation presents great difficulties. So we propose a novel thread pre-construction concept for SMT processor to decompose the thread fetch schedule into two related schedules. The threadpre-costruction schedule focuses on reducing wrong path instruction ratio;the ready thread fetch schedule focuses on reducing Instruction Queue（IQ）clog.Also,athread buffer structure is proposed to implenent the thread pre-construction mechanism.Simulation results obtained by SMTSIM tool set ,shown in Figs,3,4,and 5 in the full paper,show preliminarily that using the novel thread pre-construction concept improves the processor＇s performance by 9.39%over that of the standard SMTprocessor with ICOUNT2.8 policy.