Subject: "partial" container checkpoint
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: Oren Laadan <orenl@cs.columbia.edu>, xemul@parallels.com,
       containers@lists.linux-foundation.org, mingo@elte.hu,
       linux-kernel@vger.kernel.org, hch@infradead.org,
       akpm@linux-foundation.org, torvalds@linux-foundation.org,
       Alexey Dobriyan <adobriyan@gmail.com>
In-Reply-To: <20090414152951.GA7703@us.ibm.com>
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	 <20090413214701.GA24509@us.ibm.com> <49E424A3.60606@cs.columbia.edu>
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Date: Tue, 14 Apr 2009 09:37:03 -0700
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On Tue, 2009-04-14 at 10:29 -0500, Serge E. Hallyn wrote:
> I think the perceived need for it comes, as above, from the pure
> checkpoint-a-whole-container-only view.  So long as you will
> checkpoint/restore a whole container, then you'll end up doing
> something requiring privilege anyway.  But that is not all of
> the use cases.

Yeah, there are certainly a lot of shades of gray here.  I've been
talking to some HPC guys in the last couple of days.  They certainly
have a need for checkpoint/restart, but much less of a need for doing
entire containers.  

It also occurs to me that we have the potential to pull some
long-out-of-tree users back in.  VMADump users, for instance:

	http://bproc.sourceforge.net/c268.html

If we could do *just* a selective checkpoint of a single process's VMAs,
the bproc users could probably use sys_checkpoint() in some way.  That's
*way* less than an entire container, but it would be really useful to
some people.   

-- Dave

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