本文選題：嵌入式實(shí)時(shí)系統(tǒng)　切入點(diǎn)：亂序處理器　出處：《華中科技大學(xué)》2012年碩士論文

【摘要】：嵌入式多媒體流計(jì)算具有軟實(shí)時(shí)特性，對(duì)其進(jìn)行自適應(yīng)調(diào)節(jié)要求計(jì)算過程具有可預(yù)測性。亂序處理器通過在一個(gè)時(shí)鐘周期內(nèi)發(fā)射多條指令以亂序方式執(zhí)行，導(dǎo)致計(jì)算時(shí)間難以預(yù)測，限制了其在嵌入式實(shí)時(shí)系統(tǒng)中的應(yīng)用。因此迫切需要發(fā)展對(duì)亂序處理器指令吞吐量進(jìn)行動(dòng)態(tài)平穩(wěn)化的方法，以提高程序執(zhí)行時(shí)間的可預(yù)測性。 在分析固定系數(shù)比例積分微分（PID）動(dòng)態(tài)平穩(wěn)化亂序處理器指令吞吐量局限性的基礎(chǔ)上，提出了基于變速積分PID的亂序處理器指令吞吐量動(dòng)態(tài)調(diào)節(jié)方法。通過分析亂序處理器的執(zhí)行機(jī)制及其指令吞吐量變化特征，，發(fā)現(xiàn)亂序處理器在提高處理器指令執(zhí)行效率和資源利用率的同時(shí)，也使得其執(zhí)行指令過程變得復(fù)雜和不可預(yù)測。其指令吞吐量具有高度可變性，指令執(zhí)行具有很大的不確定性。指令吞吐量最大值最高可達(dá)到最小值的4倍之多。而且，在程序?qū)嶋H運(yùn)行時(shí)，指令吞吐量發(fā)生突變的情形相當(dāng)普遍�；诠潭ㄏ禂�(shù)PID反饋的調(diào)節(jié)方法雖然可以平穩(wěn)化程序緩變時(shí)的指令吞吐量，但是，當(dāng)程序發(fā)生突變時(shí)，由于固定系數(shù)PID反饋控制器的積分系數(shù)對(duì)系統(tǒng)誤差的累積太大，導(dǎo)致系統(tǒng)在目標(biāo)值附近振蕩而不收斂。針對(duì)基于固定系數(shù)PID控制器的局限性，提出了變速積分PID控制算法。其能根據(jù)系統(tǒng)偏差的值動(dòng)態(tài)調(diào)節(jié)積分系數(shù)，從而得到不同的PID控制量，通過動(dòng)態(tài)電壓頻率調(diào)節(jié)（DVFS）機(jī)制，來平穩(wěn)化非平穩(wěn)變化程序的指令吞吐量。 實(shí)驗(yàn)結(jié)果表明，變速積分PID控制算法不僅能調(diào)節(jié)程序平穩(wěn)變化的指令吞吐量，對(duì)非平穩(wěn)化變化的指令吞吐量，在經(jīng)過一段時(shí)間的調(diào)節(jié)后，也能較快地收斂于目標(biāo)吞吐量，從而實(shí)現(xiàn)指令吞吐量的平穩(wěn)化，具有較好的調(diào)節(jié)效果。通過平穩(wěn)化亂序處理器的指令吞吐量，可以更好地預(yù)測應(yīng)用程序的執(zhí)行時(shí)間。這無論是對(duì)于保證系統(tǒng)的實(shí)時(shí)性要求，還是提高系統(tǒng)自適應(yīng)調(diào)節(jié)的有效性，都具有重要的潛在應(yīng)用價(jià)值。
[Abstract]:Embedded multimedia stream computing has the characteristic of soft real time, and the calculation process is required to be predictable when it is adjusted adaptively.In a single clock cycle, the scrambled processor transmits multiple instructions to execute in a scrambled manner, which makes the computing time difficult to predict and limits its application in embedded real-time systems.Therefore, there is an urgent need to develop a method of dynamically stabilizing the instruction throughput of scrambled processors in order to improve the predictability of program execution time.On the basis of analyzing the limitation of instruction throughput of fixed coefficient proportional integral differential (PD) processor, a dynamic adjustment method of instruction throughput based on variable speed integral PID is proposed.By analyzing the execution mechanism of the scrambled processor and the characteristics of its instruction throughput, it is found that the scrambled processor not only improves the efficiency of instruction execution and resource utilization, but also makes the instruction execution process complex and unpredictable.Its instruction throughput is highly variable and instruction execution is uncertain.The maximum instruction throughput can be as many as four times the minimum.Moreover, when the program actually runs, the instruction throughput mutation situation is quite common.Although the regulation method based on fixed coefficient PID feedback can stabilize the instruction throughput when the program changes slowly, but when the program changes suddenly, because the integral coefficient of the fixed coefficient PID feedback controller accumulates too much system error,The system oscillates and does not converge near the target value.Aiming at the limitation of PID controller based on fixed coefficient, a variable speed integral PID control algorithm is proposed.It can dynamically adjust the integral coefficient according to the value of the system deviation, and obtain different PID control quantities. By adjusting the dynamic voltage frequency to adjust the VFS mechanism, the instruction throughput of the non-stationary program can be stabilized.The experimental results show that the variable-speed integral PID control algorithm can not only adjust the variable instruction throughput of the program, but also converge to the target throughput after a period of time adjustment.Thus, the instruction throughput is smooth and has good adjustment effect.The execution time of the application can be predicted better by stabilizing the instruction throughput of the scrambled processor.It has important potential application value both to guarantee the real-time requirement of the system and to improve the effectiveness of the adaptive regulation of the system.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：TP332

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本文編號(hào)：1715241