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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] [PATCH V2] balloon: Don't try fetching info if machine is stopped |
Date: | Thu, 26 Aug 2010 08:22:31 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100713 Lightning/1.0b1 Thunderbird/3.0.6 |
On 08/26/2010 03:14 AM, Daniel P. Berrange wrote:
On Thu, Aug 26, 2010 at 10:05:44AM +0200, Paolo Bonzini wrote:On 08/26/2010 08:05 AM, Amit Shah wrote:This is what I have currently. It would need some timer handling in the save/load case as well, right?When loading you won't have any pending "info balloon" command, so I think the timer need not be preserved across migration. Also, 5 seconds for a stopped guest is actually a lot, so maybe Amit's original patch or a variant thereof would make sense anyway.We should have a combination of both. If we know the guest is stopped we should return immediately, otherwise we should use the timer as a way to cope with a crashed/evil guest.
Stopped doesn't necessarily mean that it's permanently stopped or even that a user has stopped it.
We stop a guest during live migration and in some other cases (like on disk error).
Returning immediately is an optimization on something that should be a proper fix. Otherwise, you have a guest initiated DoS attack on management tools.
Regards, Anthony Liguori
Daniel
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