Collaborative Research: Algorithms Design and Systems Implementation to Improve Buffer Management for Fast I/O Data Accesses

虽然处理器周期、内存大小和磁盘容量都变得越来越丰富，但系统对处理数据密集型应用的支持仍然存在一个严重的不足，即以获取请求数据的第一个字节的时间来衡量硬盘访问的长延迟。这种延迟改进明显落后于其他系统组件的改进，包括磁盘峰值带宽。为了解决这一关键问题，调查人员将开发新的高效缓冲区缓存管理系统，以适应急剧的技术变化和具有复杂访问模式的数据密集型应用的高要求。为了使内存缓冲区成为应用程序请求和磁盘提供的服务之间真正有效的代理，研究人员将利用内存缓冲区中的缓存和预取机制，通过最小化昂贵的磁盘访问的成本(包括能量和时间)来提高应用程序所感知的有效I/O系统性能。研究中采用的一种独特的方法是将磁盘布局信息直接放在缓冲区管理的地图上，并有效地整合时间和空间位置。调查人员将设计和实施一个系统基础设施，分析和利用磁盘上的数据布局信息。有了这一关键的系统支持，研究人员将进一步设计和实现双端感知的内存缓冲区管理算法，以适应程序端和磁盘端表现出的特征。

Although processor cycles, memory size, and disk capacity all become increasingly abundant, there is still a serious deficiency in the system support for handling data-intensive applications, which is the long latency of hard disk accesses, measured by the time to get the first byte of requested data. This latency improvement has significantly lagged behind other system component improvement, including disk peak bandwidth. To address this critical issue, the investigators will develop new and efficient buffer cache management systems that adapt to the dramatic technology changes and the high demand of data-intensive applications with complicated access patterns. Aiming at making the memory buffer as a truly effective agent between the requests from applications and services provided by disks, the investigators will leverage the cache and prefetch mechanisms in the memory buffer to improve effective I/O system performance, perceived by applications, by minimizing the cost (both energy and time) of expensive disk accesses. A unique approach to be adopted in the research is to put the disk layout information directly on the map of buffer management and effectively integrate both temporal and spatial localities. The investigators will design and implement a system infrastructure that analyzes and exploits data layout information on disks. With this critical system support, the investigators will further design and implement dual-side-aware memory buffer management algorithms that adapt to characteristics exhibited at both programs' side and disks' side.