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From: "Denis V. Lunev" <den@openvz.org>
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Date: Mon, 14 Mar 2016 18:00:40 +0300
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Subject: Re: [Qemu-devel] [PATCH 6/9] log: log QMP commands and replies
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To: "Daniel P. Berrange" <berrange@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: Pavel Butsykin <pbutsykin@virtuozzo.com>, qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>, Luiz Capitulino <lcapitulino@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>

On 03/14/2016 05:38 PM, Daniel P. Berrange wrote:
> On Mon, Mar 14, 2016 at 03:33:53PM +0100, Paolo Bonzini wrote:
>>
>> On 14/03/2016 12:21, Denis V. Lunev wrote:
>>> From: Pavel Butsykin <pbutsykin@virtuozzo.com>
>>>
>>> This log would be very welcome for long-term diagnostics of the system
>>> in the production. This log is at least necessary to understand what
>>> has been happened on the system and to identify issues at higher-level
>>> subsystems (libvirt, etc).
>>>
>>> These messages will be quite useful to understand how things are going.
>> There is now a logging mechanism for qemu-char.c.  Have you looked into
>> making libvirt provide a QMP log based on it?
>>
>> The timestamping of patch 9 could be useful for character devices as well.
> libvirt QEMU driver already has logging support for recording all the data
> it both sends and receives over QMP, which should be sufficient for any
> day to day troubleshooting of QMP issues. So I doubt duplicating that
> info from QEMU side too is really beneficial for debugging issues when
> libvirt is in use.
>
> In libvirtd set
>
>    log_filters="1:qemu_monitor"
>
> and it'll capture everything on the QMP monitor in the default libvirtd
> log file.
>
> The QMP data is also fed into the libvirt tracing backend, so you can
> write systemtap scripts that hook on any QMP message, reply or event.
> We ship a sample monitoring script examples/systemtap/qemu-monitor.stp
> for this too.
>
> Regards,
> Daniel
you definitely sold this to me :) Thank you for pointing this out.

OK. This means that patches 5-9 are not that necessary.

Den