Edward, In the test_resize_cq test the following is written # Fill the CQ entries except one for avoid cq_overrun warnings. send_wr, _ = u.get_send_elements(self.client, False) ah_client = u.get_global_ah(self.client, self.gid_index, self.ib_port) for i in range(self.client.cq.cqe - 1): u.send(self.client, send_wr, ah=ah_client) # Decrease the CQ size to less than the CQ unpolled entries. new_cq_size = 1 with self.assertRaises(PyverbsRDMAError) as ex: self.client.cq.resize(new_cq_size) self.assertEqual(ex.exception.error_code, errno.EINVAL) No where does it make any attempt to see if the sends are completed before testing to resize the cq. Software drivers might not get finished in time and fail the test because there are no entries in the cq. Technically this is wrong code. You should test for the completion before attempting to destroy them. Or insert a small delay. Bob