Using Lightweight Procedures to Improve Instruction Cache Performance

Instruction cache performance is widely recognized as a critical component of the overall performance of a program; especially so in the case of large applications like database servers. In this report, we present a technique for (1) identifying repeated blocks of instructions in a program executable, and (2) converting these repeated code blocks into lightweight procedures (i.e. LWprocs). The use of LWprocs reduces the static code size of a program, and can potentially reduce the working set size of the process, at the cost of increasing its dynamic instruction count. However, the tradeoo seems to be in favor of the reduction in working set size for most programs. Even with a simple model of program structure and a straightforward technique for generating LWprocs, we nd performance improvements between 3% to 9% for programs in the SPECINT95 suite. However, the technique sometimes leads to slowdowns (between 5% and 27%) for some programs, suggesting that lightweight procedures should be used with care.