CSR---PDOS: Log-Based Architectures: Extending Chip Multiprocessors to Help Software Behave Correctly

由于错误、安全攻击和间歇性硬件错误，软件的错误行为过于频繁。虽然过去已经开发了强大的工具？称为？救生员？？来在程序执行时对其进行监视，以便发现问题，有时甚至在问题发生时进行修复，但这些工具在历史上运行得如此缓慢(通常是一个数量级的减慢)，以至于在现场连续运行它们是不切实际的。为了解决这个问题，该项目正在开发一种新的通用框架，该框架利用芯片多处理器中的空闲处理器核心，使强大的救生员能够在已部署的代码上连续运行，以便检测、诊断和修复不正确的行为，而不会给用户带来明显的成本。这个新的救生员框架中的一个关键技术是一种新的机制，用于通过由硬件捕获、由操作系统管理并暴露给救生员软件的日志来高效地动态检查和倒带程序。该项目预计将在以下方面产生影响。首先也是最重要的是，它应该使软件更加健壮，不仅允许现有的救生员在现场连续运行，而且希望通过催生比我们今天拥有的更复杂和更有用的新救生员。这些工具对程序员来说尤其重要，因为他们在为芯片多处理器编写并行程序时试图避免正确性和性能错误。这项新服务将通过并行机提供一种新类型的终端用户价值，超越原始加速比(即提高了对软件错误、安全攻击和其他错误的稳健性)。硬件生成的日志的存在还可能导致编写软件的新方式(例如，通过检查其过去的行为或利用日志作为恢复机制)。

Software misbehaves too frequently due to bugs, security attacks, and intermittent hardware errors. While powerful tools?called ?lifeguards??have been developed in the past to monitor a program as it executes for the sake of detecting and sometimes even fixing problems as they happen, these tools have historically run so slowly (often an order of magnitude slowdown) that it was impractical to run them continuously in the field. To address this problem, this project is developing a new general-purpose framework that harnesses idle processor cores in a chip multiprocessor to enable powerful lifeguards to run continuously on deployed code in order to detect, diagnose, and fix incorrect behaviors with no perceived cost to the user. A key technology in this new lifeguard framework is a novel mechanism for efficient dynamic program inspection and rewind via a log that is captured by the hardware, managed by the operating system, and exposed to the lifeguard software. This project is expected to have impact in the following ways. First and foremost, it should make software more robust, not only by allowing existing lifeguards to be run continuously in the field, but also by hopefully spawning the creation of new lifeguards that are even more sophisticated and useful than what we have today. These tools will be especially important for programmers as they try to avoid correctness and performance bugs when they write parallel programs for chip multiprocessors. This new service will provide a new type of end-user value from a parallel machine beyond raw speedup (i.e. improved robustness against software bugs, security attacks, and other errors). The existence of a hardware-generated log may also lead to new ways to write software (e.g., by inspecting its past behavior or exploiting the log as a recovery mechanism).