[Simh] Excessive paging of the real machine running SIMH - VAX

[Richard Davis]

HI.

I've just trawled through the numerous archives and came across this thread
(Sept 2006), it sounds remarkably like the symptoms I'm seeing on my host
machine, it unfortunately makes the whole machine (emulated and host
machine) grind almost to a halt.
Using the 'Windoze task manager' to see what is going on, it seems that SIMH
task goes page fault crazy and is doing a horrendous amount of 'I/O write
bytes', this either occurs just after the VMS 
"WBM-I-WBMINFO Write Bitmap has successfully completed initialization." Or
immediately the first disk mount occurs during the VMS startup, occasionally
(only VERY occasionally) everything works just fine and the emulated
MicroVax starts up and operates correctly.

Has anyone determined exactly what is going on and any possible
workarounds/fixes?

My host machine is: 3Ghz Pentium4 with hyperthreading enabled, 3Gb RAM
running XP sp2.
My SIMH emulated machine: MicroVax 3900 with 64m memory, a RA72 as system
disk and a "RAUSER=8380080" (RZ29) running VMS 7.1

Thanks
  Richard