Message-ID: <4CD850C0.7020609@cs.columbia.edu>
Date: Mon, 08 Nov 2010 14:34:24 -0500
From: Oren Laadan <orenl@cs.columbia.edu>
Organization: Columbia University
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To: Gene Cooperman <gene@ccs.neu.edu>
CC: Kapil Arya <kapil@ccs.neu.edu>, Tejun Heo <tj@kernel.org>,
        linux-kernel@vger.kernel.org, hch@lst.de,
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Subject: Re: [Ksummit-2010-discuss] checkpoint-restart: naked patch
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On 11/08/2010 01:37 PM, Gene Cooperman wrote:
> Thanks for the careful response, Oren.  For others who read this,
> one could interpret Oren's rapid post as criticizing the work of
> Andres Lagar Cavilla.  I'm sure that this was not Oren's intention.
> Please read below for a brief clarification of the novelty of SnowFlock.

Err... yes, that was careless of me. I was too focused on
getting the thread back to track. Thanks for pointing out.

>>> about live migration, have you also looked at the work of
>>> Andres Lagar Caviilla on SnowFlock?
>>>      http://andres.lagarcavilla.com/publications/LagarCavillaEurosys09.pdf
>>> He does live migration of entire virtual machines, again with very
>>> small delay.  Of course, the issue for any type of live migration is that
>>> if the rate of dirtying pages is very high (e.g. HPC), then there is
>>> still a delay or slow response, due to page faults to a remote host.
>>
>> VMware, Xen and KVM already do live migration. However, VMs
>> are a separate beast.
>
> I absolutely agree with your point that live migration of
> applications is a different beast, and technically very novel.
>      Since I know Andres Lagar Cavilla personally, I also feel obligated
> to comment why SnowFlock truly is novel in the VM space.  First, as Andres
> writes:
> "SnowFlock is an open-source project [SnowFlock] built on the Xen 3.0.3
> VMM [Barham 2003]."
> In the abstract, Andres points out one of the major points of novelty:
> "To evaluate SnowFlock, we focus on the demanding
> scenario of services requiring on-the-fly creation of hundreds
> of parallel workers in order to solve computationallyintensive
> queries in seconds."
> We must be careful that we don't destroy someone's reputation without
> a careful study of their work.

Yes, it's really nice work - I saw it when I visited there.
(Coincidentally the post-copy idea with Xen appeared also in
VEE 09 briefly before).

Oren.

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