On 23 Apr 1997, Glen Stewart wrote:

> I have two questions about memory use under NetBSD...
> 
> 1. When my system starts, it says 20Mb of real memory: 16Mb avail
> 
>  - does this mean that 4Mb is being used for the system, or that

I believe so, yes.  That seems fairly reasonable.  I think it takes 3 or 4
on my IIsi, as well (but that kernel's _old_!).

>  - along with the question above, does NetBSD care how memory in
>    the two banks is organized (4-1Mb's in A, and 4-4Mb's in B); 
>    and how much memory can I successfully use with NetBSD?

I don't think it really cares what your memory config is, assuming it's a
valid configuration for the system.  I could always be wrong, though.  I
think it will support whatever the computer itself will support. 

> 2. I have 20Mb of real RAM, and a 50Mb swap.  I'm finding that
>    when about 60 processes are running (consuming 6Mb of RAM)
>    that Virtual Memory used goes up to about 45Mb.  Is it safe to
>    assume that more real RAM will decrease use of VM?

Probably.

>    I had the idea that VM was used a). to store memory images of
>    sleeping or inactive processes, and b). to "contain" active
>    processes when physical RAM is completely consumed.  If this
>    assumption is right, then why would 45Mb of VM be allocated
>    when only 6Mb of real RAM space (out of 20) is needed?

I'm not sure.  Possibly, though.  Somebody else could probably answer
this better than I.

> If this situation is anything like NetScape's cache, maybe I'd be
> better off to just eliminate/minimize cache and keep my real RAM
> high?

I'm pretty sure you do have to have at least as much swap as RAM.  If you
run out of swap, the system will almost definitely hang....

> These questions are stimulated by trying to fix a very sluggish
> system that is too disk-I/O bound.  I'm thinking that if I can 
> just reduce disk I/O, the thing will run more efficiently.  As it
> now stands, it gets so busy I can hardly type on it.

Eeew.  What are those processes, and are you sure that they're not taking
lots more RAM than they appear to be?


Later,

 /---------------------------------------------------------------------\
|David A. Gatwood             And Richard Cory, one calm summer night,  |
|davagatw@mars.utm.edu      Went home and put a bullet through his head.|
|dgatwood@globegate.utm.edu          --Edwin Arlington Robinson         |
|-----------------------------------------------------------------------|
|http://globegate.utm.edu                  http://www.utm.edu/~davagatw |
|http://mars.utm.edu/~davagatw             http://www.nyx.net/~dgatwood |
 \---------------------------------------------------------------------/