Re: [Ksummit-2010-discuss] checkpoint-restart: naked patch

From: Oren Laadan
Date: Mon Nov 08 2010 - 14:31:24 EST




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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