@@ -208,6 +208,58 @@ class ThrottleTestCase(iotests.QMPTestCase):
limits[tk] = rate
self.do_test_throttle(ndrives, 5, limits)
+ # Test that removing a drive from a throttle group should not
+ # affect the remaining members of the group.
+ # https://bugzilla.redhat.com/show_bug.cgi?id=1535914
+ def test_remove_group_member(self):
+ # Create a throttle group with two drives
+ # and set a 4 KB/s read limit.
+ params = {"bps": 0,
+ "bps_rd": 4096,
+ "bps_wr": 0,
+ "iops": 0,
+ "iops_rd": 0,
+ "iops_wr": 0 }
+ self.configure_throttle(2, params)
+
+ # Read 4KB from drive0. This is performed immediately.
+ self.vm.hmp_qemu_io("drive0", "aio_read 0 4096")
+
+ # Read 4KB again. The I/O limit has been exceeded so this
+ # request is throttled and a timer is set to wake it up.
+ self.vm.hmp_qemu_io("drive0", "aio_read 0 4096")
+
+ # Read from drive1. We're still over the I/O limit so this
+ # request is also throttled. There's no timer set in drive1
+ # because there's already one in drive0. Once the timer in
+ # drive0 fires and its throttled request is processed then the
+ # next request in the queue will be scheduled: this one.
+ self.vm.hmp_qemu_io("drive1", "aio_read 0 4096")
+
+ # At this point only the first 4KB have been read from drive0.
+ # The other requests are throttled.
+ self.assertEqual(self.blockstats('drive0')[0], 4096)
+ self.assertEqual(self.blockstats('drive1')[0], 0)
+
+ # Remove drive0 from the throttle group and disable its I/O limits.
+ # drive1 remains in the group with a throttled request.
+ params['bps_rd'] = 0
+ params['device'] = 'drive0'
+ result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **params)
+ self.assert_qmp(result, 'return', {})
+
+ # Removing the I/O limits from drive0 drains its pending request.
+ # The read request in drive1 is still throttled.
+ self.assertEqual(self.blockstats('drive0')[0], 8192)
+ self.assertEqual(self.blockstats('drive1')[0], 0)
+
+ # Advance the clock 5 seconds. This completes the request in drive1
+ self.vm.qtest("clock_step %d" % (5 * nsec_per_sec))
+
+ # Now all requests have been processed.
+ self.assertEqual(self.blockstats('drive0')[0], 8192)
+ self.assertEqual(self.blockstats('drive1')[0], 4096)
+
class ThrottleTestCoroutine(ThrottleTestCase):
test_img = "null-co://"
@@ -1,5 +1,5 @@
-........
+..........
----------------------------------------------------------------------
-Ran 8 tests
+Ran 10 tests
OK
A throttle group can have several members, and each one of them can have several pending requests in the queue. The requests are processed in a round-robin fashion, so the algorithm decides the drive that is going to run the next request and sets a timer in it. Once the timer fires and the throttled request is run then the next drive from the group is selected and a new timer is set. If the user tried to remove a drive from a group and that drive had a timer set then the code was not taking care of setting up a new timer in one of the remaining members of the group, freezing their I/O. This problem was fixed in 6fccbb475bc6effc313ee9481726a1748b6dae57, and this patch adds a new test case that reproduces this exact scenario. Signed-off-by: Alberto Garcia <berto@igalia.com> --- tests/qemu-iotests/093 | 52 ++++++++++++++++++++++++++++++++++++++++++++++ tests/qemu-iotests/093.out | 4 ++-- 2 files changed, 54 insertions(+), 2 deletions(-)