Re: Serious issues with xenpaging

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Jan 03, 2014 at 09:49:36AM -0500, Andres Lagar-Cavilla wrote:
> 
> On Dec 31, 2013, at 11:31 AM, Tim Deegan <tim@xen.org> wrote:
> 
> > At 10:33 -0500 on 31 Dec (1388482410), Konrad Rzeszutek Wilk wrote:
> >> On Mon, Dec 23, 2013 at 06:34:55PM +0000, Russell Pavlicek wrote:
> >>> On Twitter, Florian Heigl sent a out a few messages about issues with xenpaging:
> >>> 
> >>> ---
> >>> 19-Dec: Anyone successfully use #xen<https://twitter.com/search?q=%23xen&src=hash> #xenpaging<https://twitter.com/search?q=%23xenpaging&src=hash>? docs are at SLES manual, rest is mostly this: http://www.gossamer-threads.com/lists/xen/devel/255798<http://t.co/P36VdL84Et> dead feature or usable?
> >>> 
> >>> 22-Dec: @lars_kurth<https://twitter.com/lars_kurth> @RCPavlicek<https://twitter.com/RCPavlicek> Hey guys, I wrote down as much as I could https://piratenpad.de/p/Ik3lOBLniq1L5TEM   <https://t.co/e5LQCUD9d0> (since I'm on holiday and not constant online)
> >>> 
> >>> 22-Dec: Yay, tested #xen<https://twitter.com/search?q=%23xen&src=hash> Xenpaging (memory overcommit)
> >>> [x] largely untested
> >>> [x] docs outdated
> >>> [x] syntax+logic changed
> >>> [x] broken
> >>> ---
> >>> 
> >>> [I've taken the liberty of removing the colorful expletive from the final post]
> >>> 
> >>> Is Florian's assessment correct, or is there somewhere we can point him for help?  I'm on vacation this week, but if someone replies to me, I will try to forward the information appropriately.
> >> 
> >> The Maintainers file implies otherwise. Let me CC the maintainers.
> > 
> > Andres really owns this code, so I'll punt to him for an official
> > answer, but:
> The part actively maintained is the hypervisor support for paging, and the interface.
> 
> tools/xenpaging is one way to consume that interface. It seems to have suffered from bitrot.

What is the other interface? Thanks!
> 
> So other than echoing Tim's points below, I'll add
> 
> - Some interesting ideas thrown around by Florian in his notes. Could lead to a robust discussion in xen-devel … if Florian is still interested.
> 
> - Perhaps the developers who are interested (myself included) should make a decent effort at improving the in-tree tools. There is the argument that for example KSM gives KVM users a sharing solution that just works, whether you like the results or not. In that vein xenpaging apparently doesn't cut it, nor the absence of a basic sharing tool.
> 
> One simple paging tool could be lazy restore. There is some interest out there, it would be relatively straightforward to codify.
> 
> Andres
> > 
> > - It's been listed as a 'tech preview' on the feature list since it went
> >  in.  http://wiki.xenproject.org/wiki/Xen_Release_Features says:
> >  "Preview, due to limited tools support. Hypervisor side in good shape."
> > 
> > - I can't say anything about SuSE's apparent support for it, except
> >  that ISTR Olaf worked at/for/with SuSE at the time.
> > 
> > - Patches would, of course, be welcome.
> > 
> > Tim.
> 

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