On Sun, Sep 05, 1999 at 04:24:46PM +0930, Brett Lymn wrote:
> According to Richard Rauch:
> >
> >My understanding is that total virtual memory is essentially equal to
> >physical RAM + swap-size.  Correct?  And, although a swap-size of approx.
> >4x physical memory is recommended, there's no particular condition on the
> >size of the swap paritition.  Correct?
> >
> 
> I don't know if UVM has changed this requirement but, yes, there was a
> lower limit on the amount of swap you had (I suspect UVM has lifted
> this but...).  In older BSD systems you needed to have at least the
> same amount of swap as you had physical RAM because each memory page
> needed to be backed by a swap page.  The old rule of thumb was at
> least twice the physical RAM size was a good swap size to give you
> some pages for data.

Mach VM didn't have this limitation (and UVM doesn't either). As far as I
remenber in NetBSD the amout of virtual memory has aways been RAM + swap.
With less swap than RAM the only problem you can have is that you can't have
get core dumps from the kernel.

--
Manuel Bouyer, LIP6, Universite Paris VI.           Manuel.Bouyer@lip6.fr
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