Adding a fixture to set scheduler to slower speeds and revert it back.

tests/qos/qos_sai_base.py

@@ -2624,3 +2624,60 @@ def change_lag_lacp_timer(self, duthosts, get_src_dst_asic_and_duts, tbinfo, nbr
                     logger.info(
                         "Changing lacp timer multiplier to default for %s in %s" % (neighbor_lag_member, peer_device))
                     vm_host.no_lacp_time_multiplier(neighbor_lag_member)
+
+    def copy_and_run_set_cir_script_cisco_8000(self, dut, port, asic="", speed="10000000"):
+        if dut.facts['asic_type'] != "cisco-8000":
+            raise RuntimeError("This function should have been called only for cisco-8000.")
+        dshell_script = f'''
+from common import *
+from sai_utils import *
+
+def set_port_cir(interface, rate):
+    mp = get_mac_port(interface)
+    sch = mp.get_scheduler()
+    sch.set_credit_cir(rate)
+    sch.set_credit_eir_or_pir(rate, False)
+
+set_port_cir("{port}", {speed})
+print("success")
+'''
+        script_path = "/tmp/set_scheduler.py"
+        dut.copy(content=dshell_script, dest=script_path)
+        dut.docker_copy_to_all_asics(
+            container_name=f"syncd{asic}",
+            src=script_path,
+            dst="/")
+        asic_arg = ""
+        if asic != "":
+            asic_arg = f"-n asic{asic}"
+        output = dut.shell(f"show platform npu script {asic_arg} -s set_scheduler.py")['stdout']
+        if output != "success":
+            raise RuntimeError("Couldn't set the scheduler for this interface, pls check the DUT.")
+
+    @pytest.fixture(scope="function", autouse=False)
+    def set_cir_change(self, get_src_dst_asic_and_duts, dutConfig):
+        dst_port = dutConfig['dutInterfaces'][dutConfig["testPorts"]["dst_port_id"]]
+        dst_dut = get_src_dst_asic_and_duts['dst_dut']
+        dst_asic = get_src_dst_asic_and_duts['dst_asic']
+        dst_index = dst_asic.asic_index
+
+        if dst_dut.facts['asic_type'] != "cisco-8000":
+            yield
+            return
+        asic_arg = ""
+        if dst_index is not None:
+            asic_arg = f"-n asic{dst_index}"
+        port_speed = int(dst_dut.shell(
+            'sonic-db-cli {} APPL_DB HGET '
+            '\"PORT_TABLE:{}\" \"speed\"'.format(
+                asic_arg, dst_port))['stdout']) * 1000 * 1000
+
+        # Set scheduler to 5 Gbps.
+        self.copy_and_run_set_cir_script_cisco_8000(
+            dut=dst_dut, port=dst_port, asic=dst_index, speed=5 * 1000 * 1000 * 1000)
+
+        yield
+
+        # Set scheduler back to original speed.
+        self.copy_and_run_set_cir_script_cisco_8000(
+            dut=dst_dut, port=dst_port, asic=dst_index, speed=int(1.1*port_speed))

tests/qos/test_qos_sai.py

@@ -1517,7 +1517,7 @@ def testQosSaiDot1pPgMapping(
 
     def testQosSaiDwrr(
         self, ptfhost, duthosts, get_src_dst_asic_and_duts, dutTestParams, dutConfig, dutQosConfig, change_port_speed,
-        skip_src_dst_different_asic
+        skip_src_dst_different_asic, set_cir_change
     ):
         """
             Test QoS SAI DWRR
@@ -2061,7 +2061,7 @@ def testQosSaiSeparatedDscpToPgMapping(self, duthost, request, ptfhost,
 
     def testQosSaiDwrrWeightChange(
         self, get_src_dst_asic_and_duts, ptfhost, dutTestParams, dutConfig, dutQosConfig,
-        updateSchedProfile, skip_src_dst_different_asic
+        updateSchedProfile, skip_src_dst_different_asic, set_cir_change
     ):
         """
             Test QoS SAI DWRR runtime weight change