19.02.2020 16:16, Andrey Shinkevich wrote:
On 17/02/2020 18:02, Vladimir Sementsov-Ogievskiy wrote:
The test aims to test _postcopy_ migration, and wants to do some write
operations during postcopy time.

Test considers migrate status=complete event on source as start of
postcopy. This is completely wrong, completion is completion of the
whole migration process. Let's instead consider destination start as
start of postcopy, and use RESUME event for it.

Next, as migration finish, let's use migration status=complete event on
target, as such method is closer to what libvirt or another user will
do, than tracking number of dirty-bitmaps.

Finally, add a possibility to dump events for debug. And if
set debug to True, we see, that actual postcopy period is very small
relatively to the whole test duration time (~0.2 seconds to >40 seconds
for me). This means, that test is very inefficient in what it supposed
to do. Let's improve it in following commits.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
  tests/qemu-iotests/199 | 72 +++++++++++++++++++++++++++++++++---------
  1 file changed, 57 insertions(+), 15 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index dda918450a..6599fc6fb4 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -20,17 +20,43 @@
  import os
  import iotests
-import time
  from iotests import qemu_img
+debug = False
+
  disk_a = os.path.join(iotests.test_dir, 'disk_a')
  disk_b = os.path.join(iotests.test_dir, 'disk_b')
  size = '256G'
  fifo = os.path.join(iotests.test_dir, 'mig_fifo')
+def event_seconds(event):
+    return event['timestamp']['seconds'] + \
+        event['timestamp']['microseconds'] / 1000000.0
+
+
+def event_dist(e1, e2):
+    return event_seconds(e2) - event_seconds(e1)
+
+
  class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
      def tearDown(self):
It's common to put the definition of setUp() ahead

+        if debug:
+            self.vm_a_events += self.vm_a.get_qmp_events()
+            self.vm_b_events += self.vm_b.get_qmp_events()
+            for e in self.vm_a_events:
+                e['vm'] = 'SRC'
+            for e in self.vm_b_events:
+                e['vm'] = 'DST'
+            events = (self.vm_a_events + self.vm_b_events)
+            events = [(e['timestamp']['seconds'],
+                       e['timestamp']['microseconds'],
+                       e['vm'],
+                       e['event'],
+                       e.get('data', '')) for e in events]
+            for e in sorted(events):
+                print('{}.{:06} {} {} {}'.format(*e))
+
          self.vm_a.shutdown()
          self.vm_b.shutdown()
          os.remove(disk_a)
@@ -47,6 +73,10 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
          self.vm_a.launch()
          self.vm_b.launch()
+        # collect received events for debug
+        self.vm_a_events = []
+        self.vm_b_events = []
+
      def test_postcopy(self):
          write_size = 0x40000000
          granularity = 512
@@ -77,15 +107,13 @@ class 
TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
              self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
              s += 0x10000
-        bitmaps_cap = {'capability': 'dirty-bitmaps', 'state': True}
-        events_cap = {'capability': 'events', 'state': True}
+        caps = [{'capability': 'dirty-bitmaps', 'state': True},
The name "capabilities" would be an appropriate identifier.

+                {'capability': 'events', 'state': True}]
-        result = self.vm_a.qmp('migrate-set-capabilities',
-                               capabilities=[bitmaps_cap, events_cap])
+        result = self.vm_a.qmp('migrate-set-capabilities', capabilities=caps)
          self.assert_qmp(result, 'return', {})
-        result = self.vm_b.qmp('migrate-set-capabilities',
-                               capabilities=[bitmaps_cap])
+        result = self.vm_b.qmp('migrate-set-capabilities', capabilities=caps)
          self.assert_qmp(result, 'return', {})
          result = self.vm_a.qmp('migrate', uri='exec:cat>' + fifo)
@@ -94,24 +122,38 @@ class 
TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
          result = self.vm_a.qmp('migrate-start-postcopy')
          self.assert_qmp(result, 'return', {})
-        while True:
-            event = self.vm_a.event_wait('MIGRATION')
-            if event['data']['status'] == 'completed':
-                break
+        e_resume = self.vm_b.event_wait('RESUME')
"event_resume" gives a faster understanding

+        self.vm_b_events.append(e_resume)
          s = 0x8000
          while s < write_size:
              self.vm_b.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
              s += 0x10000
+        match = {'data': {'status': 'completed'}}
+        e_complete = self.vm_b.event_wait('MIGRATION', match=match)
"event_complete" also

+        self.vm_b_events.append(e_complete)
+
+        # take queued event, should already been happened
+        e_stop = self.vm_a.event_wait('STOP')
"event_stop"

+        self.vm_a_events.append(e_stop)
+
+        downtime = event_dist(e_stop, e_resume)
+        postcopy_time = event_dist(e_resume, e_complete)
+
+        # TODO: assert downtime * 10 < postcopy_time

I got the results below in debug mode:

That's why it's a TODO


downtime: 6.194924831390381
postcopy_time: 0.1592559814453125
1582102669.764919 SRC MIGRATION {'status': 'setup'}
1582102669.766179 SRC MIGRATION_PASS {'pass': 1}
1582102669.766234 SRC MIGRATION {'status': 'active'}
1582102669.768058 DST MIGRATION {'status': 'active'}
1582102669.801422 SRC MIGRATION {'status': 'postcopy-active'}
1582102669.801510 SRC STOP
1582102675.990041 DST MIGRATION {'status': 'postcopy-active'}
1582102675.996435 DST RESUME
1582102676.111313 SRC MIGRATION {'status': 'completed'}
1582102676.155691 DST MIGRATION {'status': 'completed'}

+        if debug:
with no usage in the following patches, you can put the whole block of relative code 
above under the "if debug: section

TODO will be uncommented soon


+            print('downtime:', downtime)
+            print('postcopy_time:', postcopy_time)
+
+        # Assert that bitmap migration is finished (check that successor bitmap
+        # is removed)
          result = self.vm_b.qmp('query-block')
-        while len(result['return'][0]['dirty-bitmaps']) > 1:
-            time.sleep(2)
-            result = self.vm_b.qmp('query-block')
+        assert len(result['return'][0]['dirty-bitmaps']) == 1
+        # Check content of migrated (and updated by new writes) bitmap
          result = self.vm_b.qmp('x-debug-block-dirty-bitmap-sha256',
                                 node='drive0', name='bitmap')
-
          self.assert_qmp(result, 'return/sha256', sha256)


Reviewed-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com>


--
Best regards,
Vladimir

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