DEVICE state was introduced back in 2017:
https://lore.kernel.org/qemu-devel/20171020090556.18631-1-dgilbert@redhat.com/
Quote from Dave's cover letter, when the pre-switchover phase was enabled,
the state transition looks like this:
The precopy flow is:
active->pre-switchover->device->completed
The postcopy flow is:
active->pre-switchover->postcopy-active->completed
To supplement above, when the cap is not enabled:
The precopy flow is:
active->completed
The postcopy flow is:
active->postcopy-active->completed
It works for us, though we have some code just to special case these state
transitions, so the DEVICE state currently is special only to precopy, and
only conditionally.
I had a quick discussion with Libvirt developers, it turns out that this
may not be necessary. IOW, it seems okay we can have DEVICE state to be
generic, so that we don't have over-complicated state machines. It not
only helps align all the migration state machine, help cleanup the code
path especially on pre-switchover handling (see the patch itself), another
side benefit is we can unconditionally have a specific state to mark the
switchover phase, which might be helpful for debugging too.
This patch makes the DEVICE state to be present always, marking that source
QEMU is switching over. Then the state machine will be always as simple
as:
active-> [pre-switchover->] -> device -> [postcopy-active->] -> complete
After the change, no matter whether pre-switchover or postcopy is enabled
or not, we always have DEVICE state showing the switchover phase. When
pre-switchover enabled, we'll have an extra stage before that. When
postcopy is enabled, we'll have an extra stage after that.
A few qtests need touch up in QEMU tree for this change:
- A few iotest outputs (194, 203, 234, 262, 280)
- Teach libqos's migrate() on "device" state
Cc: Jiri Denemark <jdenemar@redhat.com>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Cc: Dr. David Alan Gilbert <dave@treblig.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-15-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
When dumping an object into the log, there are differences between
Python 2 and 3. First, unicode strings are prefixed by 'u' in Python 2
(they are no longer in 3, because unicode strings are the default
there). Second, the order of keys in dicts may differ. Third,
especially long numbers are longs in Python 2 and thus get an 'L'
suffix, which does not happen in Python 3.
We can get around all of these differences by dumping objects (lists and
dicts) in a language-independent format, namely JSON. The JSON
generator even allows emitting dicts with their keys sorted
alphabetically.
This changes the output of all tests that use these logging functions
(dict keys are ordered now, strings in dicts are now enclosed in double
quotes instead of single quotes, the 'L' suffix of large integers is
dropped, and "true" and "false" are now in lower case).
The quote change necessitates a small change to a filter used in test
207.
Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-Id: <20181022135307.14398-10-mreitz@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
There is a race between the test's 'query-migrate' QMP command after the
QMP 'STOP' event and completing the migration:
The test case invokes 'query-migrate' upon receiving 'STOP'. At this
point the migration thread may still be in the process of completing.
Therefore 'query-migrate' can return 'status': 'active' for a brief
window of time instead of 'status': 'completed'. This results in
qemu-iotests 203 hanging.
Solve the race by enabling the 'events' migration capability, which
causes QEMU to emit migration-specific QMP events that do not suffer
from this race condition. Wait for the QMP 'MIGRATION' event with
'status': 'completed'.
Reported-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20180305155926.25858-1-stefanha@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This test case will prevent future regressions with savevm and
IOThreads.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20171207201320.19284-7-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
