Hercules vs z/PDT - some observations
I received some time ago results from a handful of
runs done on a
z/PDT V1.7 system. Took some time to analyze,
the data and full analysis is now under
Performance testing of z/PDT is explicitly disallowed in the z/PDT license conditions. s370_perf would be not the proper tool any way. The page cited above merely gives some observations on general features of z/PDT, the key ones are repeated here
- z/PDT is based on on-the-fly binary translation, see section background.
- z/PDT does an optimizing compilation, see section code optimization.
- the same code is sometimes compiled, sometimes not, see section to compile or not to compile.
- if code is compiled, compilation can happen with substantial delay, see section compilation delay.
- performance in plain interpretive mode seems similar to Hercules, see section interpreter mode performance.
- RR instructions is the easy part, see section RR instructions.
- RX instructions is the hard part, see section RX instructions.
- z/PDT vs Hercules comparisons difficult to interpret, see section z/PDT vs Hercules.
- little gain for floating point arithmetic, see section floating point performance.
- a bit faster for decimal packed arithmetic, see section decimal packed performance.
EXis apparently always interpreted, see section EX instruction.
- z/PDT performs well for some instructions which are slow on Hercules, see sections CLCL, MVCIN, and TRT.
- overall JIT gain depends heavily on workload, see bottom line.
For any further background and detail follow the links.
Any remarks and comments are very welcome.