[Simh] EXT :Re: some performance issues

Hittner, David T [US] (MS) david.hittner at ngc.com
Wed Mar 6 13:46:01 EST 2019


So from a performance analysis perspective, what are the VUPS ratings of the VS4000-90 and the SIMH VAX running on the RX2800?
That's (more or less) the Integer performance rating.

David

-----Original Message-----
From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of gérard Calliet
Sent: Wednesday, March 6, 2019 1:11 PM
To: Pontus Pihlgren <pontus at Update.UU.SE>
Cc: simh at trailing-edge.com
Subject: EXT :Re: [Simh] some performance issues

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
>>
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