Re: [Qemu-devel] [PATCH v4 0/8] Obtain dirty bitmap via VM logging

[Eric Blake]

On 07/17/2014 05:21 AM, Sanidhya Kashyap wrote:
> Hi,
> 
> The following patches introduce the support of the dirty bitmap logging and
> dumping to a specified file. This patch addresses the previous issues raised
> by David and Juan. Since, I have not received any comments on the runstates,
> I'll keep them in the patch series.

I'm really not sure you need to be introducing a new runstate.  I'm not
an expert in runstates, but it feels fishy to me - adding a new state
causes all sorts of complications (can I pause a domain that is logging
a bitmap? If I resume a paused domain, does it resume back to normal
running or back to logging?).  We _don't_ have a new state for block
jobs, and this feels similar to a block job.  Remember, it is still
possible to block migration for the duration of certain block jobs.  If
that was your goal (prevent migration and logging at the same time,
because they stomp over each other's use of the dirty bitmap), then I
think it would be sufficient to have this behave more like a block job
that can inhibit migration, but not as an entirely new runstate.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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