[Simh] some performance issues

[gérard Calliet]

The reason was "you can do everything with 2 OpenVMS/Itanium boxes" 
(they are Itanium I4)

Gérard Calliet

Le 06/03/2019 à 16:54, Zane Healy a écrit :
> I have to wonder if a lightweight Linux disto, that has been locked down, running on a Core i7 might not give better SIMH performance.  My *old* i7 ESXI box provides a faster “VAX” than my VAXstation 4000/60.
>
> What is the reason for running on Itanium?
>
> Zane
>
>
>
>> On Mar 6, 2019, at 1:57 AM, Pontus Pihlgren <pontus at Update.UU.SE> wrote:
>>
>> Hi
>>
>> I'm having trouble understanding your question. Are
>> you comparing CPU-time of a real VAX(which model?) to
>> emulated CPU-time on an Itanium machine(which one?).
>>
>> Emulation will have an associated overhead. If you
>> are compareing a fast VAX to an emulation on a slow
>> Itanium... well, Itanium is hard to optimize for.
>>
>> /P
>>
>> On Tue, Mar 05, 2019 at 03:13:53PM +0100, gérard Calliet wrote:
>>> Hello,
>>>
>>> Again I have some performance issues with simh.
>>>
>>> I built it  on OpenVMS Itanium. It runs on a process with enought
>>> memory, it takes 1 of the 8 CPU Itanium with 100%, no page faults,
>>> and 100 BIO by second.
>>>
>>> On the emulated VAX we are running processes CPU intensive (old Ada
>>> compiler), they take 100% of the CPU, also very few page fault, very
>>> few IO.
>>>
>>> And the CPU time is about 2 or 3 times the CPU time on the hardware,
>>> and so elapsed time 3 or 4 times. (For my understanding, it is
>>> difficult to think the same stream of instructions can use different
>>> CPU times between hardware and SIMH).
>>>
>>> Where can I do something to improve performance? Are there
>>> parameters (or constant in compilation) in SIMH which could help?
>>> And the specific context is processes doing almost only CPU
>>> computing.
>>>
>>>
>>>>>>> my configuration, and what commit I use
>>> on error continue
>>> load -r ka655x.bin
>>> attach NVR ka655.nvr
>>> set cpu 512m
>>> set cpu conhalt
>>> set RL disable
>>> set LPT disable
>>> set TQ disable
>>> set -L rq0 rauser=18000000
>>> attach rq0 datauser2.dsk
>>> set xq mac=08-00-2B-3C-96-75
>>> attach xq eth0
>>> dep bdr 0
>>> b cpu
>>>
>>>
>>> $ run vax-i64
>>> MicroVAX 3900 simulator V4.0-0 Beta        git commit id: 8810571d
>>> sim>
>>>
>>>
>>> Thanks,
>>>
>>> Gérard Calliet
>>>
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>>> Simh at trailing-edge.com
>>> http://mailman.trailing-edge.com/mailman/listinfo/simh
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>