[Info-vax] Floating point emulation of OpenVMS / Alpha / ES

[abrsvc]

On Monday, October 31, 2022 at 6:54:42 PM UTC-4, Hans Bachner wrote:
> Nick K schrieb am 12.10.2022 um 16:26: 
> > Most of what I'm looking at is single-threaded software, think Fortran scientific applications that have been around for a really long time. The newer versions were compiled with the IEEE floating points (T), the older versions were not. If I narrow things down to a half dozen emulators I want to look into, and all vendors want to give me a trial, this would still take a week or two, for me to configure systems and run benchmarks (unfortunately, my boss has other ideas for my time). This is why I'm asking if something is already available, or heuristically known. SpecFP? FLOPS? Emulator vendor A's pet project is IO bound, emulator vendor B's pet project is Int bound, emulator vendor C's pet project is Fortran bound? Given that EmuVM and AVT have offices that are 5 km apart, I assume there must be some significant differences between all the various emulators.
> from your base note:
> > I'm curious what to expect when moving OpenVMS from an Alpha / ES server to a virtual machine with an emulator.
> "ES server" is a wide field with different CPUs and different performance. 
> 
> Having said that, Stromasys SA does run the old SPECfp2000 (and 
> SPECint2000) benchmarks with their CHARON-AXP emulators, incidently with 
> an ES40 configuration. I'm not sure whether the results are published 
> openly, but a Stromasys partner can probably give you a copy. You then 
> can compare the results with the original results submitted by Compaq 
> around the year 2000. 
> 
> Without going into details, the current CHARON-AXP version is faster 
> than a ES40 6/667, but a bit slower than the ES40 6/833 with the 
> SPECfp2000 tests. (Almost 40% faster than the 6/833 for SPECint2000). 
> 
> These tests were run on a Xeon 5122 3,6 GHz from 2017. With a more 
> current CPU you'll probably see better results - compare ProLiant DL380 
> results for SPECspeed2017_fp with different CPUs. 
> 
> Ask the other vendors whether they run some kind of benchmark to compare 
> the emulators with the real hardware. 
> 
> Does this help? 
> 
> Hans. 
> 
> Disclaimer: my company is a Stromasys Sales & Support Partner.
I don't have specific numbers, but Hans is correct.  The CPU performance of the Charon-AXP emulator will depend upon the underlying Core speed as well as the implementation. I am not aware of any specific numbers that are published since there are too many variables to make them meaningful.  Customers that are concerned about performance are usually requested to either provide testing programs or perform internal tests during a proof of concept trial.  Please note that there are alternatives available in the emulated environment that can improve performance over "real" hardware.  Memory size is one example.  Emulation allows for more memory to be available than in some hardware models.

Dan
Stromasys Sr. Engineer.