Re: [Qemu-devel] pause and restore function before and after QEMU Live Snapshot

[Eric Blake <eblake@redhat.com>]

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On 07/17/2014 02:20 PM, Yuanzhen Gu wrote:
> Hi Eric,

[please don't top-post on technical lists]

> I enabled libvirt debugging, and saw the log file under
> /var/log/libvirt/libvirtd.log,

Which debugging filters did you enable? In particular, you'll want to
turn on LIBVIRT_LOG_FILTERS="1:qemu" for full libvirt logging of qemu
interaction (see http://libvirt.org/logging.html for details); at which
point you can then search for QEMU_MONITOR_IO_PROCESS lines to see when
libvirt sends commands to QMP and gets replies back.  This sort of
question may be better asked on the libvirt-users@redhat.com list.

> 
> for example, I saw
> 2014-07-17 20:06:55.992+0000: 4391: debug : qemuProcessHandleResume:575 :
> Transitioned guest ubuntu out of paused into resumed state
> 
> my further question is, is there any way to locate the function call for
> pause and resume from source code, based on the log info? thanks!

Are you looking for where in the libvirt source code a snapshot manages
qemu commands?  Look for
src/qemu/qemu_driver.c:qemuDomainSnapshotCreateActiveExternal, and trace
through the code it calls for qemuDomainSnapshotFSFreeze and
qemuMonitorTransaction.

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


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