Re: physmem and swap servers

[Neal H. Walfield]

At Fri, 14 Nov 2003 10:10:05 +0100,
Ludovic Court�s wrote:
> 
> Yesterday, 14 hours, 19 minutes, 21 seconds ago, Neal H. Walfield wrote:
> > At Thu, 13 Nov 2003 17:15:22 +0100, Ludovic Court?s wrote:
> > 
> > > My question is: How would an application be able to use a custom swap
> > > server?  Would there be a special method to tell physmem that such
> > > application would like to use such swap server?
> > 
> > It just needs to send the data to the new server rather than to swap.
> > What is lost is the ability to preserve copy on write.
> 
> Do you mean pm_swap () is something optional that tasks are not
> compelled to use?  If a task doesn't use pm_swap () when it wants to
> swap out pages, then it might ask some swap server to write the frame to
> backing store and then call pm_release_frames () for that frame,
> right?

What does it mean to swap?  Save date to backing store and then free
the frame.  pm_swap () is provided by the phys mem server only because
that is the only sane way to preserve copy on write.  If you don't
care about copy on write (for example, .data and anonymous memory)
then you needn't use it.