Improve log readability & polish scenario parameters
diff --git a/src/python/grpcio_tests/tests_aio/benchmark/worker_servicer.py b/src/python/grpcio_tests/tests_aio/benchmark/worker_servicer.py
index 18a6e3f..f23b07c 100644
--- a/src/python/grpcio_tests/tests_aio/benchmark/worker_servicer.py
+++ b/src/python/grpcio_tests/tests_aio/benchmark/worker_servicer.py
@@ -34,12 +34,24 @@
 _NUM_CORES = multiprocessing.cpu_count()
 _NUM_CORE_PYTHON_CAN_USE = 1
 _WORKER_ENTRY_FILE = os.path.split(os.path.abspath(__file__))[0] + '/worker.py'
-_SubWorker = collections.namedtuple('_SubWorker',
-                                    ['process', 'port', 'channel', 'stub'])
 
 _LOGGER = logging.getLogger(__name__)
 
 
+class _SubWorker(
+        collections.namedtuple('_SubWorker',
+                               ['process', 'port', 'channel', 'stub'])):
+
+    def _repr(self):
+        return f'<_SubWorker pid={self.process.pid} port={self.port}>'
+
+    def __repr__(self):
+        return self._repr()
+
+    def __str__(self):
+        return self._repr()
+
+
 def _get_server_status(start_time: float, end_time: float,
                        port: int) -> control_pb2.ServerStatus:
     end_time = time.time()
@@ -231,9 +243,8 @@
             for worker in sub_workers:
                 await worker.stub.QuitWorker(control_pb2.Void())
                 await worker.channel.close()
-                _LOGGER.info('Waiting for sub worker [%s] to quit...', worker)
+                _LOGGER.info('Waiting for [%s] to quit...', worker)
                 await worker.process.wait()
-                _LOGGER.info('Sub worker [%s] quit', worker)
 
     async def _run_single_client(self, config, request_iterator, context):
         running_tasks = []
diff --git a/tools/run_tests/performance/scenario_config.py b/tools/run_tests/performance/scenario_config.py
index b7791af..c8c7f88 100644
--- a/tools/run_tests/performance/scenario_config.py
+++ b/tools/run_tests/performance/scenario_config.py
@@ -829,27 +829,34 @@
         return 1200
 
     def scenarios(self):
-        yield _ping_pong_scenario(
-            'python_asyncio_protobuf_async_unary_ping_pong_64_max',
-            rpc_type='UNARY',
-            client_type='ASYNC_CLIENT',
-            server_type='ASYNC_SERVER',
-            outstanding=64,
-            channels=1,
-            unconstrained_client='async',
-            categories=[SMOKETEST, SCALABLE])
+        for outstanding in [32, 64, 128, 256]:
+            for channels in [1, 5]:
+                yield _ping_pong_scenario(
+                    'python_asyncio_protobuf_async_unary_ping_pong_%dx%d_max' %
+                    (
+                        outstanding,
+                        channels,
+                    ),
+                    rpc_type='UNARY',
+                    client_type='ASYNC_CLIENT',
+                    server_type='ASYNC_SERVER',
+                    outstanding=outstanding,
+                    channels=channels,
+                    unconstrained_client='async',
+                    categories=[SMOKETEST, SCALABLE])
 
-        yield _ping_pong_scenario(
-            'python_asyncio_protobuf_async_unary_ping_pong_128_1thread',
-            rpc_type='UNARY',
-            client_type='ASYNC_CLIENT',
-            server_type='ASYNC_SERVER',
-            outstanding=128,
-            channels=1,
-            async_client_threads=1,
-            async_server_threads=1,
-            unconstrained_client='async',
-            categories=[SMOKETEST, SCALABLE])
+            yield _ping_pong_scenario(
+                'python_asyncio_protobuf_async_unary_ping_pong_%d_1thread' %
+                outstanding,
+                rpc_type='UNARY',
+                client_type='ASYNC_CLIENT',
+                server_type='ASYNC_SERVER',
+                outstanding=outstanding,
+                channels=1,
+                async_client_threads=1,
+                async_server_threads=1,
+                unconstrained_client='async',
+                categories=[SMOKETEST, SCALABLE])
 
         yield _ping_pong_scenario(
             'python_asyncio_generic_async_streaming_ping_pong',