Re: [Qemu-devel] [libvirt] [PATCHv2] Don't log an internal error when the guest hasn't updated balloon stats

[Ján Tomko]

On 05/16/2014 03:13 PM, Luiz Capitulino wrote:
> On Fri, 16 May 2014 00:11:24 -0600
> Eric Blake <address@hidden> wrote:
> 
>>> Is "no stats yet" really an error? 
> 
> This is a special case where the guest hasn't ever filled QEMU with balloon
> stats. There are two possible cases. Either the guest hasn't done it yet, but
> will do in the future or the guest will never do it (eg. the guest doesn't
> support balloon, the guest crashed, etc).
> 
>>> Libvirt has done nothing wrong, and
>>> I'd argue the guest hasn't done anything wrong, either.  Should we
>>> simply return an empty result?  Like "cat" on a file that hasn't gotten
>>> its data, yet.
>>
>> Yes, that would be reasonable.
> 
> I'm fine with the two possible solutions here: adding a new TryAgain error
> class or returning an "empty" result.
> 
> I say "empty" because those fields are not optionals, so we'll have to fill
> them with some value. Shouldn't be a problem for most fields, as the spec
> (docs/virtio-balloon-stats.txt) already defines that stats that the guest
> doesn't report are returned as -1. The only exception here is the last-update
> field, which can't hold a negative iirc. The only choice is to return 0 there.
> I guess that this shouldn't be a problem either.
> 
> Who volunteers to fix this?
> 

I've tried:

http://marc.info/?l=qemu-devel&m=140048179520115&w=2

Jan

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