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Date: Tue, 14 Apr 2009 19:27:52 +0400
From: Alexey Dobriyan <adobriyan@gmail.com>
To: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: akpm@linux-foundation.org, containers@lists.linux-foundation.org,
       xemul@parallels.com, dave@linux.vnet.ibm.com, mingo@elte.hu,
       orenl@cs.columbia.edu, hch@infradead.org, torvalds@linux-foundation.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/30] cr: core stuff
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References: <20090410023539.GK27788@x200.localdomain> <20090413214701.GA24509@us.ibm.com>
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On Mon, Apr 13, 2009 at 04:47:01PM -0500, Serge E. Hallyn wrote:
> Quoting Alexey Dobriyan (adobriyan@gmail.com):
> 
> Hi Alexey,
> 
> as far as I can see, the main differences between this patch and the
> equivalent in Oren's tree are:
> 
> 1. kernel auto-selects container init to freeze

Note, auto-select part was dropped, userspace is required to pass pid of
container init exactly. This was done to keep semantic of checkpoint(2)
small and extendable.

> 2. kernel freezes tasks
> 3. no objhash taking references

That's because none needed.

> 4. no hbuf

hbuf is an optimization to not allocate/free memory for every image.
For a start it's unnecessary complication, I just kzalloc/dump/kfree.

> 5. always require CAP_SYS_ADMIN
> 
> Are there other differences which you would consider meaningful?  Which
> do you consider the most important?
> 
> Also, since Dave introduced the fops->checkpoint(), we (or at least I)
> have been struck by the ugly assymetry with checkpoint() being in fops,
> and restart() not.  Do you have an idea for fixing that?

Module can legally support C/R for its files.

In the end it most certainly will end up with module registering restart
hook for file type N.

Or module registering hook to restart object type N.

This is for discussion.
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