CSR-EHS: Memory management as a run-time service

SRAM存储器对于改善运行时间、能源使用和实时边界至关重要。许多嵌入式处理器包含刮擦存储器（SPM），这是一种未增强的SRAM，映射到地址空间的一部分。它们提供了比缓存更好的实时保证，缓存是另一种SRAM内存类型。将对象自动分配给SPM的编译器方法已经存在了十年，但是最近的一项调查甚至没有发现一个商业编译器可以自动分配SPM。相反，程序员使用注释手动指定SPM分配。原因可能包括开发人员不了解SPM，不愿意在工具链中包含另一个特性，以及在每个编译器中重复实现的费用。本研究正在开发一种完全在二进制重写器内部实现的SPM分配策略。这个二进制重写器在程序第一次载入内存时由操作系统自动调用。随后的执行在没有额外开销的情况下获得SPM的好处。这种方法使SPM第一次成为运行时提供的资源，就像缓存和虚拟内存一样，使其对软件工具链来说无处不在且透明。该研究的更广泛的影响是：(i)嵌入式系统以更低的成本实现高速和实时行为；（ii）耗电量较低、电池寿命较长的手提装置；（iii）可移植到任何SPM大小的程序？重要的实际优势；（iv）教育和推广计划，包括研究生培训、本科和研究生课程、实习和记忆管理研讨会。

SRAM memories are essential to improving run-time, energy use and real-time bounds. Many embedded processors contain Scratch Pad Memory (SPM), unenhanced SRAM that is mapped to a portion of the address space. They offer better real-time guarantees than caches, an alternate SRAM memory type. Compiler methods to allocate objects automatically to SPM have existed for a decade, but a recent survey did not find even a single commercial compiler that does automatic SPM allocation. Instead, programmers manually specify the SPM allocation using annotations. Reasons may include developer unawareness of SPM, unwillingness to include another feature in the toolchain, and the expense of repeated implementation in each compiler. This research is developing a SPM allocation strategy that is completely implemented inside a binary rewriter. This binary rewriter is called automatically by the operating system the first time the program is loaded to memory. Subsequent executions derive the benefits of SPM with no additional overhead. This approach makes SPM a run-time-provided resource for the first time, much like cache and virtual memory are, making it ubiquitous and transparent to the software toolchain. The broader impacts of the research are (i) embedded systems that achieve high speed and real-time behavior at lower cost; (ii) portable devices with lower energy use, hence longer battery life; (iii) programs that are portable to any SPM size ? an important practical advantage; (iv) an educational and outreach program including graduate student training, undergraduate and graduate courses, internships, and a workshop on memory management.