Hercules vs Sim390 - a comparison
Michael Short was so kind as to run a
s370_perf
version ported to
MUSIC/SP
on his
Sim390
emulator-based system.
The different OS should have no sizable impact on the measured instruction
timings since SVC and privileged instructions, which depend on
system response times, aren't covered.
A reference run with Hercules 4.0 on the same host CPU is available too.
The data and full analysis are under
https://github.com/wfjm/s370-perf/blob/master/narr/2018-07-30_ms1-herc40.md
https://github.com/wfjm/s370-perf/blob/master/narr/2018-07-30_ms1-sim390.md
https://github.com/wfjm/s370-perf/blob/master/narr/2018-07-30_ms1-sim390.md
The key findings are
- Sim390 is, on identical Host hardware, a factor is a factor 6.5 slower than Hercules 4.0, based on the lmark MIPS ratio of 6.39 to 41.54.
- simple instructions, like
LR R,R, are about a factor 9 slower, see section LR timing. - branch timing does not depend on same/different page, see section branch timing.
CLCLandTRTare much faster on Sim390, see section CLCL+TRT performance.
The overall summary is that Hercules has much more efficient handling of instruction fetch and decoding and virtual to real address mapping.
Any remarks and comments are very welcome.
2018-12-27: MVCIN, CLCL and TRT performance significantly improved
in Hercules Release V4.1, see
this short note.
For original posting to
Yahoo! Group - Hercules-390
see
topic 84175.
Dead link since 2020-12-15: Yahoo! Groups
was discontinued by Verizon.