MaxSim: A simulation platform for managed applications

Managed applications, written in programming languages such as Java, C# and others, represent a significant share of workloads in the mobile, desktop, and server domains. Microarchitectural timing simulation of such workloads is useful for characterization and performance analysis, of both hardware and software, as well as for research and development of novel hardware extensions. This paper introduces MaxSim, a simulation platform based on the Maxine VM, the ZSim simulator, and the McPAT modeling framework. MaxSim is able to simulate fast and accurately managed workloads running on top of Maxine VM and its capabilities are showcased with novel simulation techniques for: 1) low-intrusive microarchitectural profiling via pointer tagging on the x86-64 platforms, 2) modeling of hardware extensions related, but not limited to, tagged pointers, and 3) modeling of complex software changes via address-space morphing. Low-intrusive microarchitectural profiling is achieved by utilizing tagged pointers to collect type- and allocation-site-related hardware events. Furthermore, MaxSim allows, through a novel technique called address space morphing, the easy modeling of complex object layout transformations. Finally, through the codesigned capabilities of MaxSim, novel hardware extensions can be implemented and evaluated. We showcase MaxSim's capabilities by simulating the whole set of the DaCapo-9.12-bach benchmarks in less than a day while performing an up-to-date microarchitectural power and performance characterization. Furthermore, we demonstrate a hardware/software co-designed optimization that performs dynamic load elimination for array length retrieval achieving up to 14% L1 data cache loads reduction and up to 4% dynamic energy reduction. MaxSim is available at https://github.com/arodchen/MaxSim released as free software.