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Message-ID: <49B9D9B9.4070508@cs.columbia.edu>
Date: Thu, 12 Mar 2009 23:57:45 -0400
From: Oren Laadan <orenl@...columbia.edu>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: linux-api@...r.kernel.org, containers@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org,
Dave Hansen <dave@...ux.vnet.ibm.com>, linux-mm@...ck.org,
viro@...iv.linux.org.uk, hpa@...or.com, mingo@...e.hu,
torvalds@...ux-foundation.org, tglx@...utronix.de
Subject: Re: [RFC v13][PATCH 00/14] Kernel based checkpoint/restart
Oren Laadan wrote:
> Hi,
>
> Just got back from 3 weeks with practically no internet, and I see
> that I missed a big party !
>
> Trying to catch up with what's been said so far --
[...]
>>>>
>>>> - Will any of this involve non-trivial serialisation of kernel
>>>> objects? If so, that's getting into the
>>>> unacceptably-expensive-to-maintain space, I suspect.
>>> We have some structures that are certainly tied to the kernel-internal
>>> ones. However, we are certainly *not* simply writing kernel structures
>>> to userspace. We could do that with /dev/mem. We are carefully pulling
>>> out the minimal bits of information from the kernel structures that we
>>> *need* to recreate the function of the structure at restart. There is a
>>> maintenance burden here but, so far, that burden is almost entirely in
>>> checkpoint/*.c. We intend to test this functionality thoroughly to
>>> ensure that we don't regress once we have integrated it.
>> I guess my question can be approximately simplified to: "will it end up
>> looking like openvz"? (I don't believe that we know of any other way
>> of implementing this?)
>>
>> Because if it does then that's a concern, because my assessment when I
>> looked at that code (a number of years ago) was that having code of
>> that nature in mainline would be pretty costly to us, and rather
>> unwelcome.
>
> I originally implemented c/r for linux as as kernel module, without
> requiring any changes from the kernel. (Doing the namespaces as a kernel
> module was much harder). For more details, see:
> https://www.ncl.cs.columbia.edu/research/migrate
oops... I meant the following link:
http://www.ncl.cs.columbia.edu/research/migration/
see, for example, the papers from DejaView (SOSP 07) and Zap (USENIX 07).
Oren.
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