[Simh] some performance issues

[gérard Calliet]

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