Tracing and Characterization of Windows NT-based System Workloads

Vol. 10 No. 1 1998 The computer architecture research community commonly uses trace-driven simulation in pursuing answers to a variety of design issues. Architects spend a significant amount of time studying the characteristics of benchmark programs by examining traces, i.e., samples taken from program execution. Popular benchmark programs include the SPEC and the BYTEmark benchmark test suites. Since the underlying assumption is that these programs generate workloads that represent user applications, today’s computer designs have been optimized based on the characteristics of these benchmark programs. Although the authors of popular benchmarks are well intentioned, the resulting workloads lack operating system execution and consequently do not represent some of the most prevalent desktop applications, e.g., Microsoft Word, Microsoft Visual C/C++, and Microsoft Internet Explorer. Such applications make heavy use of application programming interfaces (APIs), which in turn execute many instructions in the operating system. As a result, the overall performance of many desktop applications depends on efficient operating system interaction. Clearly operating system overhead can greatly reduce the benefits of a new computer design feature. Past architectural studies, however, have generally ignored operating system interaction because few tools can generate operating system–rich traces. This paper discusses the ongoing joint efforts of Northeastern University and Compaq Computer Corporation to capture operating system–rich traces on DIGITAL Alpha-based machines running the Microsoft Windows NT operating system. We argue that for traces of today’s workloads to be accurate, they must capture the operating system execution as well as the native application execution. This need to capture complete program trace information has been a driving force behind the development and use of software tools such as the PatchWrx dynamic execution-tracing toolset, which we describe in this paper. The PatchWrx toolset was originally developed by Sites and Perl at Digital Equipment Corporation’s Systems Research Center. They described PatchWrx, as developed for Windows NT version 3.5, in “Studies of Tracing and Characterization of Windows NT–based System Workloads Jason P. Casmira David P. Hunter David R. Kaeli