[Simh] some performance issues

[gérard Calliet]

Hi,

We had a VAX Station 4000-90 128M Memory.

We have a RX28000 9520 8G Memory.

Gérard Calliet

Le 06/03/2019 à 10:57, Pontus Pihlgren a écrit :
> 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
>>
>> _______________________________________________
>> Simh mailing list
>> Simh at trailing-edge.com
>> http://mailman.trailing-edge.com/mailman/listinfo/simh