Re: What can OpenVZ do?

[Ingo Molnar <mingo@elte.hu>]

* Alexey Dobriyan <adobriyan@gmail.com> wrote:

> On Fri, Feb 13, 2009 at 11:27:32AM +0100, Ingo Molnar wrote:
> > 
> > * Dave Hansen <dave@linux.vnet.ibm.com> wrote:
> > 
> > > > If so, perhaps that can be used as a guide.  Will the planned feature
> > > > have a similar design?  If not, how will it differ?  To what extent can
> > > > we use that implementation as a tool for understanding what this new
> > > > implementation will look like?
> > > 
> > > Yes, we can certainly use it as a guide.  However, there are some
> > > barriers to being able to do that:
> > > 
> > > dave@nimitz:~/kernels/linux-2.6-openvz$ git diff v2.6.27.10... | diffstat | tail -1
> > >  628 files changed, 59597 insertions(+), 2927 deletions(-)
> > > dave@nimitz:~/kernels/linux-2.6-openvz$ git diff v2.6.27.10... | wc 
> > >   84887  290855 2308745
> > > 
> > > Unfortunately, the git tree doesn't have that great of a history.  It
> > > appears that the forward-ports are just applications of huge single
> > > patches which then get committed into git.  This tree has also
> > > historically contained a bunch of stuff not directly related to
> > > checkpoint/restart like resource management.
> > 
> > Really, OpenVZ/Virtuozzo does not seem to have enough incentive to merge
> > upstream, they only seem to forward-port, keep their tree messy, do minimal
> > work to reduce the cross section to the rest of the kernel (so that they can
> > manage the forward ports) but otherwise are happy with their carved-out
> > niche market. [which niche is also spiced with some proprietary add-ons,
> > last i checked, not exactly the contribution environment that breeds a
> > healthy flow of patches towards the upstream kernel.]
> 
> Oh, cut the crap!
> 
> > Merging checkpoints instead might give them the incentive to get
> > their act together.
> 
> Knowing how much time it takes to beat CPT back into usable shape every time
> big kernel rebase is done, OpenVZ/Virtuozzo have every single damn incentive
> to have CPT mainlined.

So where is the bottleneck? I suspect the effort in having forward ported
it across 4 major kernel releases in a single year is already larger than
the technical effort it would  take to upstream it. Any unreasonable upstream 
resistence/passivity you are bumping into?

	Ingo