Shadow Profiling: Hiding Instrumentation Costs with Parallelism

In profiling, a tradeoff exists between information and overhead. For example, hardware-sampling profilers incur negligible overhead, but the information they collect is consequently very coarse. Other profilers use instrumentation tools to gather temporal traces such as path profiles and hot memory streams, but they have high overhead. Runtime and feedback-directed compilation systems need detailed information to aggressively optimize, but the cost of gathering profiles can outweigh the benefits. Shadow profiling is a novel method for sampling long traces of instrumented code in parallel with normal execution, taking advantage of the trend of increasing numbers of cores. Each instrumented sample can be many millions of instructions in length. The primary goal is to incur negligible overhead, yet attain profile information that is nearly as accurate as a perfect profile. The profiler requires no modifications to the operating system or hardware, and is tunable to allow for greater cov...

• Type: Conference
• Year: 2007
• Where: CGO
• Authors: Tipp Moseley, Alex Shye, Vijay Janapa Reddi, Dirk Grunwald, Ramesh Peri
• Keywords: CGO 2007, Negligible Overhead, Shadow Profiling, Shadow Profiling Framework, Software Engineering