Re: [Xen-devel] Serious issues with xenpaging

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Jan 03, 2014 at 04:17:43PM -0500, Andres Lagar-Cavilla wrote:
> On Jan 3, 2014, at 3:31 PM, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 
> wrote:
> 
> > On Fri, Jan 03, 2014 at 02:51:14PM -0500, Andres Lagar-Cavilla wrote:
> >> On Jan 3, 2014, at 1:41 PM, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 
> >> wrote:
> >> 
> >>> 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@xxxxxxx> 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 [x] docs outdated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!
> >> 
> >> Not sure what the question is. There is one interface. What I was 
> >> referring to, is that tools/xenpaging implements one specific paging 
> >> policy: victim selection, rate limiting, paging target, all of these are 
> >> algorithms that entirely define what bang for your money you will get.
> >> 
> > 
> > Right, but there is other code that uses this interface as well correct?
> > Is it available for users ?
> 
> That I know of, Gridcentric's product. It's available as proprietary software 
> for a fee. I am unaware of a sharing user other than Gridcentric. Virtuata 
> was a mem-event user, Gridcentric is, and others have surfaced on the list 
> (Razvan Cocajaru for instance).

In the context of 
http://wiki.xenproject.org/wiki/GSoc_2014#Lazy_restore_using_memory_paging
should that be removed then? As the dependency of it would be to first 
'un-bitrot' it and that
might take more than the original GSoC problem statement describes??

> 
> Andres
> 

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