The System-on-a-Chip Lock Cache

Shared-memory;SoC;Lock-based synchronization;Real-time systems

Akgul, Bilge Ebru Saglam ; Electrical and Computer Engineering

University:Georgia Institute of Technology

Department:Electrical and Computer Engineering

关键词: Shared-memory;    SoC;    Lock-based synchronization;    Real-time systems;   

Others  :  https://smartech.gatech.edu/bitstream/1853/5253/1/akgul_bilge_e_200405_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

In this dissertation, we implement efficient lock-based synchronization bya novel, high performance, simple and scalable hardware technique andassociated software for a target shared-memory multiprocessorSystem-on-a-Chip (SoC). The custom hardware part of our solution isprovided in the form of an intellectual property (IP) hardware unit whichwe call the SoC Lock Cache (SoCLC). SoCLC provides effective lock hand-offby reducing on-chip memory traffic and improving performance in terms oflock latency, lock delay and bandwidth consumption. The proposed solutionis independent from the memory hierarchy, cache protocol and the processorarchitectures used in the SoC, which enables easily applicableimplementations of the SoCLC (e.g., as a reconfigurable or partially/fullycustom logic), and which distinguishes SoCLC from previous approaches.Furthermore, the SoCLC mechanism has been extended to support priorityinheritance with an immediate priority ceiling protocol (IPCP) implementedin hardware, which enhances the hard real-time performance of the system.Our experimental results in a four-processor SoC indicate that SoCLC canachieve up to 37% overall speedup over spin-lock and up to 48% overallspeedup over MCS for a microbenchmark with false sharing. The priorityinheritance implemented as part of the SoCLC hardware, on the other hand,achieves 1.43X speedup in overall execution time of a robot applicationwhen compared to the priority inheritance implementation under theAtalanta real-time operating system. Furthermore, it has been shown thatwith the IPCP mechanism integrated into the SoCLC, all of the tasks of therobot application could meet their deadlines (e.g., a high priority taskwith 250us worst case response time could complete its execution in 93uswith SoCLC, however the same task missed its deadline by completing itsexecution in 283us without SoCLC). Therefore, with IPCP support, oursolution can provide better real-time guarantees for real-time systems.To automate SoCLC design, we have also developed an SoCLC-generator tool,PARLAK, that generates user specified configurations of a custom SoCLC. Weused PARLAK to generate SoCLCs from a version for two processors with 32lock variables occupying 2,520 gates up to a version for fourteenprocessors with 256 lock variables occupying 78,240 gates.