CSR: Small: Making Software Transactional Memory More than a Research Toy

现在，计算机技术似乎已经达到了登纳德缩放（Dennard scaling）的极限（提高时钟速率），软件必须变得更加并行，以便与提供更多而不是更快内核的硬件进行扩展。然而，编写正确的、可伸缩的共享内存并发程序是出了名的困难。事务性内存（TM）在可编程性、可靠性和可伸缩性方面比传统共享内存系统提供了潜在的改进。然而，它并没有实现其最初的承诺，主要是因为没有人表明如何使其切实可行。硬件制造商不愿意将硬件TM （HTM）构建到已经很复杂的缓存和内存子系统中，而软件TM （STM）则受到性能差和语义弱的困扰。该项目旨在通过研究新的研究方向，使STM真正实用，实现高性能和强语义，从而显著提高技术水平。该项目使用一种新的机制来避免非冲突访问的同步，解决了STM在现有工作中的关键成本——检测和处理冲突访问。提供广泛可用的实用STM支持的直接有益影响包括生产更可靠和可伸缩的软件系统的能力，导致用于安全和关键任务系统的软件的进步。STM的广泛使用可以帮助推动硬件支持混合硬件软件TM的商业开发，这需要实际的STM支持。研究人员与工业研究人员的接触为加强传播提供了途径。该项目生成的STM实现的公开分发为进一步的研究和开发提供了基础。一些教育和推广活动，包括课程项目、增强核心课程材料、针对少数族裔工程专业本科生的暑期桥梁项目的互动演示，以及面向未来少数族裔研究生的招聘活动，旨在培养多样化的程序员和研究人员群体，以开发未来可靠的、可扩展的软件系统。

Now that computer technology appears to have reached the limit of Dennard scaling (increasing clock rates), software must become more parallel, to scale with hardware that provides more instead of faster cores. However, writing correct, scalable shared-memory concurrent programs is notoriously difficult. Transactional memory (TM) offers potential improvements over conventional shared-memory systems in programmability, reliability, and scalability. However, it has not lived up to its initial promise, primarily because no one has shown how to make it practical. Hardware manufacturers are reluctant to build hardware TM (HTM) into already-complex cache and memory subsystems, and software TM (STM) suffers from poor performance and weak semantics. This project seeks to advance the state of the art dramatically by investigating new research directions for making STM truly practical, by achieving high performance with strong semantics. The project tackles STM's key cost in existing work -- detecting and handling conflicting accesses -- using a novel mechanism that avoids synchronization at non-conflicting accesses.Direct beneficial impacts of making widely available practical STM support include the ability to produce more reliable and scalable software systems, leading to advances in software for safety- and mission-critical systems. Widespread use of STM can help spur commercial development of hardware support for hybrid hardware-software TM, which requires practical STM support. The investigator's engagement with industrial researchers provides an avenue to enhance dissemination. Public distribution of STM implementations produced by this project provides a basis for further research and development. Several educational and outreach activities, including course projects, enhanced core course material, interactive presentations for a summer bridge program targeting minority undergraduate engineering majors, and recruiting events for prospective minority graduate students, aim to train a diverse group of programmers and researchers in developing future reliable, scalable software systems.