SHF: Small: Memory Persistency: programming paradigms for byte-addressable, non-volatile memories

十多年来，工业界和学术界的研究人员一直在寻找存储数据的新技术，以便廉价地存储大量数据并快速访问。今天，计算机系统通常有三种类型的数据存储：用于廉价但缓慢、长期、批量数据存储的旋转磁盘；主存用于快速，但昂贵的数据访问应用程序正在积极使用；还有闪存，它的工作方式和旋转磁盘很像，但每比特的价格更高，存取速度更快。然而，我们现在正处于新存储技术可用性的尖端，这些新存储技术提供接近主存的性能，但可以持久地存储数据。也就是说，当电脑断电的时候？在闪存和主存储器之间的每比特成本。这些新的非易失性存储器设备在存储器和FLASH之间的计算机系统数据存储层次中增加了一个新的层。在十年内，采用这种新型非易失性存储器的系统将得到广泛应用。事实上，随着成本和制造工艺的提高，这种存储器可能成为“物联网”中小型设备的首选存储，并成为云系统中性能和可恢复性的关键。这些新的存储器开辟了探索新的格式和结构的可能性，以便在计算机系统电源故障时存储数据。与磁盘和FLASH不同，非易失性存储器中的数据可以以非常细的粒度访问。单个数据项（例如，字节）？而不是粗粒度的数据块。这种细粒度访问使数据结构的开发能够在意外断电的情况下可靠地存储数据，而且比磁盘或FLASH上的数据存储具有更高的性能和简单性。现有的计算机主存系统在设计时并没有考虑到电源故障时的持久性，因为当电源故障时数据会丢失，因此没有试图保持数据写入内存的任何特定顺序。但是，如果在写操作过程中电源故障，控制数据写入的顺序对于允许系统恢复并继续操作至关重要。该研究项目将为程序员开发新的方法，使他们能够高效、轻松地设计高性能数据结构，通过仔细控制数据记录的顺序，可以从意外故障中恢复。这项研究将与工业界密切合作，并与主要研究人员进行整合。操作系统和并行计算机体系结构课程。

For over a decade, researchers in industry and academia have sought new techniques to store data so vast amounts of data can be stored inexpensively and accessed quickly. Today, computer systems typically have three kinds of data storage: rotating disks for cheap-but-slow, long-term, bulk data storage; main memory for fast, but expensive access to data applications are actively using; and FLASH, which behaves much like rotating disks, but offers somewhat faster access at a higher price per bit. However, we are now at the cusp of availability of new storage technologies that offer performance close to that of main memory, but can store data durably?that is, when the computer is powered off?at a cost per bit between Flash and main memory. These new non-volatile memory devices add a new layer to the computer system data storage hierarchy between memory and FLASH. Within a decade, systems incorporating these new non-volatile memories will become widely available. Indeed, as cost and manufacturing processes improve, such memories may become the preferred storage for small devices in the ``Internet of Things'' and become critical to performance and recoverability in cloud systems. These new memories open up the possibility to explore new formats and structures for storing data across computer system power failures. Unlike disk and FLASH, data in non-volatile memories can be accessed at very fine granularity?individual data items (e.g., bytes)?rather than coarse-grained blocks of data. This fine-grain access enables the development of data structures that reliably store data even if power fails unexpectedly, but with greater performance and simplicity than data storage on disk or FLASH. Existing computer main memory systems have not been designed with durability across power failures in mind, since the data is lost when power fails, and therefore do not try to maintain any specific order in which data is written to memory. However, controlling this order of writing data is critical to allowing a system to recover and continue operation if power fails while writes are in progress. This research project will develop new ways for programmers to efficiently and easily design high-performance data structures that can recover from unexpected failures by carefully controlling the order in which data is recorded. The research will be performed in close collaboration with industry, and integrated with the principal investigators? course offerings in operating systems and parallel computer architecture.