Re: Making tmpfs reserved memory configurable

[Eduardo Horvath <eeh%NetBSD.org@localhost>]

On Thu, 5 Jun 2014, Martin Husemann wrote:

> On Fri, May 30, 2014 at 04:56:01PM +0200, Martin Husemann wrote:
> > I have been on a quest to make the stock vax install CD (-image) usable on
> > VAX machines with 8 MB recently. (8 MB is the lowest I could persuade simh
> > to emulate, for 4 MB we will need a custom kernel anyway and for smaller
> > even a custom /boot - I will cover installing on those machines in an
> > upcoming improvement of the install docs).
> 
> Ok, this (much simpler) patch makes tmpfs work on low memory machines.
> Comments?

Have you tested this?

The way the old scanner used to work, it started when the number of free 
pages hit freemin, and continued scanning until the number of free pages 
hit freetarg.

Looking at the code, it appears now the page scanner starts running when 
the number of free pages goes below uvmpd.freetarg.  I'm a bit concerned 
that if tmpfs allocates enough pages to put the system permanently below 
the uvmpd.freetarg threshold, the page scanner will never stop running.  
I'm not sure if this would be a problem or not, so it would be good to put 
a system into that condition to know for sure.

Eduardo