Characterization of Contemporary Workloads

Abstract: Complete system simulation to understand the influence of architecture and operating systems on application execution has been identified to be crucial for systems design. This problem is particularly interesting in the context of Java since it is not only the application that can invoke kernel services, but so does the underlying Java Virtual Machine (JVM) implementation which runs these programs. Further, the JVM style (JIT compiler or interpreter) and the manner in which the different JVM components (such as the garbage collector and class loader) are exercised, can have a significant impact on the kernel activities. To investigate these issues, this chapter uses complete system simulation of the SPECjvm98 benchmarks on the SimOS simulation platform. The execution of these benchmarks on both JIT compilers and interpreters is profiled in detail. The kernel activity of SPECjvm98 applications constitutes up to 17% of the execution time in the large dataset and up to 31% in the small dataset. Of the kernel services, TLB miss handling (utlb), file I/O system call (read) and page allocation routine (demand_zero) are the most dominant in all applications. In addition to such execution profiles, the ILP in the user and kernel mode are also quantified. The Java code is seen to limit exploitable parallelism and aggressive instruction issue is seen to be less efficient for SPECjvm98 benchmarks. Also, the kernel mode of execution does not exhibit as much ILP as the user mode.