Re: [Xen-devel] Copy-on-write memory to allow many more xenU domains per machine

[<ur...@re...>]

Check the s/390 port of the kernel for the XIP2 filesystem.  It exploits
the z/VM shared memory system to make a read-only ext2 like filesystem
that is shared amonst all the guests - and uses execute-in-place.  Any
binaries on the xip2 filesystem aren't cached into local shared memory,
they're just mapped across.

This lets an admin build explicit shared systems, does shared ro-memory
nicely, etc.  Might be worth looking into implementing similar in Xen.

Apologies if this was already discussed/noticed,

-m

On Tue, Nov 02, 2004 at 09:33:00PM +0000, Ian Pratt wrote:
>  
> > What about having a special variant of the pte-update operation, which 
> > takes as input a pointer to a pte-entry, and will change that entry into 
> > a read-only mapping of the same page contents, though perhaps with a 
> > different frame number in the pte.
> 
> I'm still not convinced we wouldn't get most of the benefit by
> just sharing pages read from the block/file system, and hence
> avoiding all the hashing. 
> 
> Collecting this data is actually very easy -- its just a case of
> coming up with a few "realistic usage scenarios" in which to
> collect the data. We'd be happy to work with someone to do
> this...
> 
> Ian
> 
> 
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