From b7213030fd59c6169b9a2d4cb9680cf5adbfe6d8 Mon Sep 17 00:00:00 2001
From: Miguel Angel Ajo <mangelajo@redhat.com>
Date: Tue, 7 Feb 2017 16:21:16 +0100
Subject: [PATCH] Simplify the QoS bandwidth test to increase reliability

The initial implementation was measuring the bandwidth stability
over segments of time. But recent failures on high gate pressure
has shown that such stability can't be expected on the edge.

The test now checks the average bandwidth during the whole transmission.

Change-Id: Ic6a00f20ce76aba319ecdada79f68599c891cf29
Closes-Bug: #1662109
---
 neutron/tests/tempest/scenario/test_qos.py | 45 ++++++++--------------
 1 file changed, 15 insertions(+), 30 deletions(-)

diff --git a/neutron/tests/tempest/scenario/test_qos.py b/neutron/tests/tempest/scenario/test_qos.py
index b5584382d1b..8b8e90a22a6 100644
--- a/neutron/tests/tempest/scenario/test_qos.py
+++ b/neutron/tests/tempest/scenario/test_qos.py
@@ -38,7 +38,6 @@ def _try_connect(host_ip, port):
         client_socket = socket.socket(socket.AF_INET,
                                       socket.SOCK_STREAM)
         client_socket.connect((host_ip, port))
-        client_socket.setblocking(0)
         return client_socket
     except socket.error as serr:
         if serr.errno == errno.ECONNREFUSED:
@@ -97,10 +96,6 @@ class QoSTest(base.BaseTempestTestCase):
                 file=QoSTest.FILE_PATH)
 
     def _check_bw(self, ssh_client, host, port):
-        total_bytes_read = 0
-        cycle_start_time = time.time()
-        cycle_data_read = 0
-
         cmd = "killall -q nc"
         try:
             ssh_client.exec_command(cmd)
@@ -109,36 +104,26 @@ class QoSTest(base.BaseTempestTestCase):
         cmd = ("(nc -ll -p %(port)d < %(file_path)s > /dev/null &)" % {
                 'port': port, 'file_path': QoSTest.FILE_PATH})
         ssh_client.exec_command(cmd)
+
+        start_time = time.time()
         client_socket = _connect_socket(host, port)
+        total_bytes_read = 0
 
         while total_bytes_read < QoSTest.FILE_SIZE:
-            try:
-                data = client_socket.recv(QoSTest.BUFFER_SIZE)
-            except socket.error as e:
-                if e.args[0] in [errno.EAGAIN, errno.EWOULDBLOCK]:
-                    continue
-                else:
-                    raise
+            data = client_socket.recv(QoSTest.BUFFER_SIZE)
             total_bytes_read += len(data)
-            cycle_data_read += len(data)
-            time_elapsed = time.time() - cycle_start_time
-            should_check = (time_elapsed >= 5 or
-                            total_bytes_read == QoSTest.FILE_SIZE)
-            if should_check:
-                LOG.debug("time_elapsed =  %(time_elapsed)d,"
-                          "total_bytes_read = %(bytes_read)d,"
-                          "cycle_data_read = %(cycle_data)d",
-                          {"time_elapsed": time_elapsed,
-                           "bytes_read": total_bytes_read,
-                           "cycle_data": cycle_data_read})
 
-                if cycle_data_read / time_elapsed > QoSTest.LIMIT_BYTES_SEC:
-                    # Limit reached
-                    return False
-                else:
-                    cycle_start_time = time.time()
-                    cycle_data_read = 0
-        return True
+        time_elapsed = time.time() - start_time
+        bytes_per_second = total_bytes_read / time_elapsed
+
+        LOG.debug("time_elapsed = %(time_elapsed)d, "
+                  "total_bytes_read = %(total_bytes_read)d, "
+                  "bytes_per_second = %(bytes_per_second)d",
+                  {'time_elapsed': time_elapsed,
+                   'total_bytes_read': total_bytes_read,
+                   'bytes_per_second': bytes_per_second})
+
+        return bytes_per_second <= QoSTest.LIMIT_BYTES_SEC
 
     @test.idempotent_id('1f7ed39b-428f-410a-bd2b-db9f465680df')
     def test_qos(self):