CRII: SHF CSR: A High Performance and Reliable Non-Volatile Memory Framework for Handheld Platforms

如今，智能手机、平板电脑和可穿戴设备等手持平台主导着半导体市场。越来越苛刻的程序由用户在由电池供电的手持平台上运行。因此，专门的硬件组件，即IP核，被引入来改进手持设备？能源效率。然而，CPU和IP的内存访问模式截然不同，这使得主存成为手持系统的关键瓶颈。非易失性存储器，特别是STT-MRAM，正在作为现有基于DRAM的主存储器的替代品而出现，实现了各种优点。然而，在手持设备中用STT-MRAM取代DRAM也带来了新的设计挑战，如读取干扰。因此，本课题提出了两种读干扰缓解方案，构建了一个高性能、高可靠的手持平台存储框架。本研究提出了一种灵活的STT-MRAM读方案，即FlexRead，以优化手持平台在读干扰下的性能和能效。FlexRead结合了现有两种数据传感方案的优点，根据运行时系统状态动态发布最佳传感方案。此外，提出了一种应用流模式预测方案，即FlowPaP，以识别和删除最初为防止读取干扰而需要的不必要的内存恢复。FlowPaP分析手持设备上运行的应用程序中的数据流行为，识别出内存处于交替写入和读取的一致循环中。这两个方案优化了多个手持平台的设计方面，从而对手持研究社区、工业产品甚至社会产生了变革性的影响。发现的阅读干扰问题是对未来手持平台世代的一个重要而现实的设计挑战。此外，拟议的研究还可以帮助国际和平研究所教授的课程和研究研讨会，还可以促进对来自高度不同背景的学生的教育，例如来自STEM领域代表性不足群体的学生。

Handheld platforms, such as smartphones, tablets, and wearable devices, nowadays dominate the semiconductor market. Increasingly demanding programs are run by users on handheld platforms powered by batteries. Therefore, specialized hardware components, i.e., IP cores, are introduced to improve handhelds? energy efficiency. However, the memory access patterns of CPUs and IPs are dramatically different, making main memory a critical bottleneck for a handheld system. Non-volatile memories, particularly STT-MRAM, are emerging as replacements for the existing DRAM-based main memory, achieving a wide variety of advantages. Nevertheless, substituting DRAM with STT-MRAM in handhelds also results in new design challenges such as read disturbance. Consequently, two read disturbance mitigation schemes are proposed in this project, constructing a high performance and reliable memory framework for handheld platforms.In this research, a flexible STT-MRAM read scheme, namely FlexRead, is proposed to optimize handheld platform performance and energy efficiency under read disturbance. FlexRead combines the advantages of two existing data sensing schemes, dynamically issuing the best sensing scheme based on the runtime system state. Furthermore, an application flow pattern prediction scheme, namely FlowPaP, is proposed to identify and remove unnecessary memory restores originally required for preventing read disturbance. FlowPaP analyzes the data flow behavior in the applications running on handhelds, recognizing that the memory is in a consistent loop of being alternately written and read. These two proposed schemes optimize multiple handheld platform design aspects, thus having a transformational impact on the handheld research community, industrial products, and even society. The discovered read disturbance issue is an important and realistic design challenge for future handheld platform generations. Moreover, the proposed research can benefit the courses and research seminar taught by the PI, also advancing the education of students from highly diverse backgrounds, e.g., those from under-represented groups in the STEM field.