Subject: Process sizes, etc...
To: None <>
From: Anders Magnusson <>
List: port-vax
Date: 03/11/2002 21:45:36
There has been problem with default max process sizes for VAXen for
some years; because of some strange law of Nature programs tend to 
grow bigger and bigger :-)

The problem has been that the user process page tables take too much 
space on the system page table, and therefore didn't allow for 
small-memory machines to boot. I wrote some code a couple of years
ago that used a smaller submap for the user page table and then 
throwed out processes when it was too crowded. This performed very
badly when there were many processes competing about the upt submap,
so I put it on the "tested project" heap.

I have now restored that code and added some intelligence to free
idle processes upt space, using the same principles that the normal
swapper does. This behave very well, and I actually managed to boot
a tailored kernel on a 2MB microvax, though it was _very_ slow...
compiling "Hello world" took 12 minutes :-)

The upt is now sized so that it do not take more than 5% of available
memory, giving it a reasonable size.

So, the process size problem should be solved now :-)

-- Ragge