Messages in this thread | | | Date | Mon, 22 Nov 2010 12:34:54 -0500 (EST) | From | Oren Laadan <> | Subject | Re: [Ksummit-2010-discuss] checkpoint-restart: naked patch |
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On Sun, 21 Nov 2010, Gene Cooperman wrote:
> Below, we'll summarize the four major questions that we've understood from > this discussion so far. But before doing so, I want to point out that a single > process or process tree will always have many possible interactions with > the rest of the world. Within our own group, we have an internal slogan: > "You can't checkpoint the world." > A virtual machine can have a relatively closed world, which makes it more > robust, but checkpointing will always have some fragile parts.
That depends of what your definition of "world". One definition is "world := VM", as you state above. Another is "world := container" which I stated in my post(s). You can checkpoint both.
For those cases where the "world" cannot be fully checkpointed, I explicitly pointed that we should focus on the core c/r functionality, because the "glue" can be done either way.
> We give four examples below: > a. time virtualization
IMHO, irrelevant to current discussion. And btw, this is done in linux-cr for live migration of tcp connections.
> b. external database > c. NSCD daemon
This falls within the category of "glue", and is - as I try once again to remind - tentirely oorthogonal to the topic of where to do c/r.
> d. screen and other full-screen text programs > These are not the only examples of difficult interactions with the > rest of the world.
This actually never required a userspace "component" with Zap or linux-cr (to the best of my knowledge)..
Even if it did - the question is not how to deal with "glue" (you demonstrated quite well how to do that with DMTCP), but how should teh basic, core c/r functionality work - which is below, and orthogonal to the "glue".
Let us please focus on the base c/r engine functionality...
(gotta disconnect now .. more later)
Oren.
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