Source Mark: A Source-Level Approach for Identifying Architecture and Optimization Agnostic Regions for Performance Analysis

Computer architects often evaluate performance on only parts of a program and not the entire program due to long simulation times that could take weeks or longer to finish. However, choosing regions of a program to evaluate in a way that is consistent and correct with respect to different compilers and different architectures is very challenging and has not received sufficient attention. The need for such tools is growing in importance given the diversity of architectures and compilers in use today. In this work, we propose a technique that identifies regions of a desired granularity for performance evaluation. We use a source-to-source compiler that inserts software marks into the program's source code to divide the execution into regions with a desired dynamic instruction count. An evaluation framework chooses from among a set of candidate marks to find ones that are both consistent across different architectures or compilers and can yield a low run-time instruction overhead. Evaluated on a set of SPEC applications, with a region size of about 100 million instructions, our technique has a dynamic instruction overhead as high as 3.3% with an average overhead of 0.47%. We also demonstrate the scalability of our technique by evaluating the dynamic instruction overhead for regions of finer granularity and show similar small overheads, of the applications we studied, we were unable to find suitable fine grained regions only for 462.libquantum and 444.namd. Our technique is an effective alternative to traditional binary-level approaches. We have demonstrated that a source-level approach is robust, that it can achieve low overhead, and that it reduces the effort for bringing up new architectures or compilers into an existing evaluation framework.