Messages in this thread | | | Date | Wed, 27 May 2009 15:40:01 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 18/38] C/R: core stuff |
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On Thu, 28 May 2009 02:17:53 +0400 Alexey Dobriyan <adobriyan@gmail.com> wrote:
> > 1) Whether or not allow c/r of sub-container (partial hierarchy) > > > > 2) Creation of restarting process hierarchy in kernel or in userspace > > > > As for #1, you are the _only_ one who advocates restricting c/r to > > a full container only. I guess you have your reasons, but I'm unsure > > what they may be. > > The reason is that checkpointing half-frozen, half-live container is > essentially equivalent to live container which adds much complexity > to code fundamentally preventing kernel from taking coherent snapshot. > > In such situations kernel will do its job badly. > > Manpage will be filled with strings like "if $FOO is shared then $BAR is > not guaranteed". > > What to do if user simply doesn't know if container is bounded? > Checkpoint and to hell with consequences? > > If two tasks share mm_struct you can't even detect that pages you dump > aren't filled with garbage meanwhile from second task. > > If two tasks share mm_struct, other task can issue AIO indefinitely > preventing from taking even coherent filesystem snapshot. > > That's why I raise this issue again to hear from people what they think > and these people shouldn't be containers and C/R people, because the > latter already made up their minds. > > This is super-important issue to get right from the beginning.
<pipes up>
yeah, checkpointing a partial hierarchy at this stage sounds like overreach. Get full-container working usably first, think about sub-containers in version 2.
<pipes down again>
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