"Gordon W. Ross" <gwr@netbsd.org> writes:
> R. C. Dowdeswell writes:
>  > 
>  > It seems to me that if we go for a strict non-overcommit strategy,
>  > then the amount of swap that we need to allocate needs to really
>  > be boosted by a huge number, and we'll never be able to get a very
>  > high usage of said swap.
>  > [...]
> 
> Not necessarily.  Budget for "anonymous" pages should be
> (swap + availmem).  Deduct from the budget whenever a new,
> writable mapping is created (map time, not fault time).
> This includes cases like a debugger remapping a text page
> read-write so it can install a breakpoint.
> [ ... ]

FWIW:

Having discussed this with a lot of people over time, the conclusion
that i've come to is that _neither_ strategy ("don't enforce safety,"
"enforce safety") will satisfy everyone.  It has to be configurable.

if done right, it should be runtime configurable:

basically, always keep track of 'safe' bounds, and allow setting of
switch for safety if you're within the safe bounds.

if the switch is set to 'safe', don't allow 'safe' bounds to be
exceeded.



cgd
-- 
Chris Demetriou - cgd@netbsd.org - http://www.netbsd.org/People/Pages/cgd.html
Disclaimer: Not speaking for NetBSD, just expressing my own opinion.