Re: How much of a mess does OpenVZ make? ;) Was: What can OpenVZdo?

[Greg Kurz]

On Fri, 2009-02-27 at 01:17 +0300, Alexey Dobriyan wrote:
> On Thu, Feb 26, 2009 at 07:30:16PM +0100, Greg Kurz wrote:
> > On Thu, 2009-02-26 at 18:33 +0100, Ingo Molnar wrote:
> > > I think the main question is: will we ever find ourselves in the 
> > > future saying that "C/R sucks, nobody but a small minority uses 
> > > it, wish we had never merged it"? I think the likelyhood of that 
> > > is very low. I think the current OpenVZ stuff already looks very 
> > 
> > We've been maintaining for some years now a C/R middleware with only a
> > few hooks in the kernel. Our strategy is to leverage existing kernel
> > paths as they do most of the work right.
> > 
> > Most of the checkpoint is performed from userspace, using regular
> > syscalls in a signal handler or /proc parsing. Restart is a bit trickier
> > and needs some kernel support to bypass syscall checks and enforce a
> > specific id for a resource. At the end, we support C/R and live
> > migration of networking apps (websphere application server for example).
> > 
> > >From our experience, we can tell:
> > 
> > Pros: mostly not-so-tricky userland code, independent from kernel
> > internals
> > Cons: sub-optimal for some resources
> 
> How do you restore struct task_struct::did_exec ?

With sys_execve().

-- 
Gregory Kurz                                     gkurz@xxxxxxxxxx
Software Engineer @ IBM/Meiosys                  http://www.ibm.com
Tel +33 (0)534 638 479                           Fax +33 (0)561 400 420

"Anarchy is about taking complete responsibility for yourself."
        Alan Moore.

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