Exploration
This section demonstrates two approaches to using the Performance Explorer
to investigate performance phenomena.
The first approach uses the Performance Explorer to look for general trends over time.
We discovered the following two unexpected instruction per cycle (IPC)
trends:
- Significant IPC improvement over time for an adaptive Jikes RVM configuration.
- Significant IPC degradation before GC.
Both trends were unknown before using the Performance Explorer.
These trends over time would be difficult, if not impossible,
to detect without a visualization tool.
The second approach uses the Performance Explorer to explore memory latency issues
with respect to the POWER4 microarchitecture.
Specifically, we used the Performance Explorer to explore the following questions:
- What is the impact on IPC and memory performance
of context switches between different Java threads?3
- How do latency issues manifest in the POWER4 memory hierarchy?
Although the answers to these two questions might have been determined by
performing a computation over the trace records directly, the Performance Explorer
provides a unified approach to explore these questions.
