An Empirical Study of the Code Pitching Mechanism in the .NET Framework

The .NET Compact Framework is designed to be a high-performance virtual machine for mobile and embedded devices that operate on Windows CE (version 4.1 and later). It achieves fast execution time by compiling methods dynamically instead of using interpretation. Once compiled, these methods are stored in a portion of the heap called the code cache and can be quickly reused to satisfy future method calls. While the code cache provides a high-level of reusability, it can also use a large amount of memory. As a result, the Compact Framework provides a “code pitching” mechanism that can be used to discard the previously compiled methods as needed. In this paper, we study the effect of code pitching on the overall performance and memory utilization of .NET applications. We conduct our experiments using Microsoft’s Shared-Source Common Language Infrastructure (SSCLI). We profile the access behavior of the compiled methods. We also experiment with various code cache configurations to perform pitching. We find that programs can operate efficiently with a small code cache without incurring substantial recompilation and execution overheads.