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Date: Tue, 01 Feb 2011 15:36:35 +0100
From: Jes Sorensen <Jes.Sorensen@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] Add virtagent file system freeze/thaw
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: agl@us.ibm.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com

On 02/01/11 15:34, Stefan Hajnoczi wrote:
> On Tue, Feb 1, 2011 at 2:26 PM, Jes Sorensen <Jes.Sorensen@redhat.com> wrote:
>> I have to admit you lost me here, where do you get that 500ms time from?
>> Is that the XMLRPC polling time or? I just used the example code from
>> other agent calls.
> 
> 500 ms is made up.  I was thinking, "what would a reasonable polling
> interval be?" and picked a sub-second number.
> 
> Can you explain how the timeout in fsfreeze can happen?  It's probably
> because I don't know the virtagent details.

Ah ok.

>>From what I understand, the XMLRPC code is setup to timeout if the guest
doesn't reply within a certain amount of time. In that case, the caller
needs to poll to wait for the guest to complete the freeze. This really
should only happen if you have a guest with a large number of very large
file systems. I don't know how likely it is to happen in real life.

Cheers,
Jes