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Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API |
Date: |
Tue, 18 Dec 2012 14:34:16 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 |
On 12/17/2012 03:13 AM, Dietmar Maurer wrote:
>> Next commit will re-enable balloon stats with a different interface, but this
>> old code conflicts with it. Let's drop it.
>
> I don't really see any conflicts here?
>
>> It's important to note that the QMP and HMP interfaces are also dropped by
>> this commit. That shouldn't be a problem though, because:
>>
>> 1. All QMP fields are optional
>> 2. This has never been really used
Libvirt has been using it when available (although reluctantly, as it
risks hanging on an uncooperative guest); and while libvirt can be
patched to call 6 QOM commands in a row to query six different QOM
stats, I still think it would be nicer to add a command that provides
all the stats at once. In particular, when calling 6 commands in
series, you no longer have an atomic picture of the guest (the polling
interval could hit between two QOM queries, resulting in a combined set
of statistics that has no counterpart to the transition of states that
the guest actually went through). On the other hand, since the stats
are already polling-based, and since it requires cooperation from the
guest, not having a guarantee of an atomic set of stats is not really
much of a loss.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [PATCH v2 0/3] re-enable balloon stats, Luiz Capitulino, 2012/12/14
- [Qemu-devel] [PATCH 3/3] docs: document virtio-balloon stats, Luiz Capitulino, 2012/12/14
- [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Luiz Capitulino, 2012/12/14
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Dietmar Maurer, 2012/12/17
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Luiz Capitulino, 2012/12/17
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Dietmar Maurer, 2012/12/17
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Luiz Capitulino, 2012/12/17
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Dietmar Maurer, 2012/12/17
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Luiz Capitulino, 2012/12/17
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API,
Eric Blake <=
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Dietmar Maurer, 2012/12/19
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Luiz Capitulino, 2012/12/19
- Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API, Eric Blake, 2012/12/20
[Qemu-devel] [PATCH 2/3] balloon: re-enable balloon stats, Luiz Capitulino, 2012/12/14
Re: [Qemu-devel] [PATCH v2 0/3] re-enable balloon stats, Dietmar Maurer, 2012/12/15