Porting 15718 to 202405: Adding a fixture to set scheduler to slower speeds and revert it back. (#16199)

Description of PR
Summary:
Fixes the flakiness of DWRR testcase. The PR adds a new fixture that slows down the scheduler without changing the underlying algorithm. This allows the dWRR test to pass consitently.


Approach
What is the motivation for this PR?
How did you do it?
How did you verify/test it?
Any platform specific information?
Supported testbed topology if it's a new test case?
Documentation

co-authorized by: [email protected]

Author: rraghav-cisco

tests/qos/qos_sai_base.py

@@ -2585,3 +2585,65 @@ def isLonglink(self, dut_host):
                     if cable_length >= 120000:
                         return True
         return False
+
+    def copy_set_cir_script_cisco_8000(self, dut, ports, asic="", speed="10000000"):
+        if dut.facts['asic_type'] != "cisco-8000":
+            raise RuntimeError("This function should have been called only for cisco-8000.")
+        dshell_script = '''
+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)
+
+'''
+
+        for intf in ports:
+            dshell_script += f'\nset_port_cir("{intf}", {speed})'
+
+        script_path = "/tmp/set_scheduler.py"
+        dut.copy(content=dshell_script, dest=script_path)
+
+        if dut.sonichost.is_multi_asic:
+            dest = f"syncd{asic}"
+        else:
+            dest = "syncd"
+        dut.docker_copy_to_all_asics(
+            container_name=dest,
+            src=script_path,
+            dst="/")
+
+    @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
+
+        interfaces = [dst_port]
+        output = dst_asic.shell(f"show interface portchannel | grep {dst_port}", module_ignore_errors=True)['stdout']
+        if output != '':
+            output = output.replace('(S)', '')
+            pattern = ' *[0-9]*  *PortChannel[0-9]*  *LACP\\(A\\)\\(Up\\)  *(Ethernet[0-9]*.*)'
+            import re
+            match = re.match(pattern, output)
+            if not match:
+                raise RuntimeError(f"Couldn't find required interfaces out of the output:{output}")
+            interfaces = match.group(1).split(' ')
+
+        # Set scheduler to 5 Gbps.
+        self.copy_set_cir_script_cisco_8000(
+            dut=dst_dut,
+            ports=interfaces,
+            asic=dst_index,
+            speed=5 * 1000 * 1000 * 1000)
+
+        yield
+        return

tests/qos/test_qos_sai.py

@@ -1540,7 +1540,7 @@ 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
@@ -2090,7 +2090,7 @@ 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

tests/saitests/py3/sai_qos_tests.py

@@ -3818,8 +3818,32 @@ def runTest(self):
                     break
                 recv_pkt = scapy.Ether(received.packet)
 
-        # Release port
-        self.sai_thrift_port_tx_enable(self.dst_client, asic_type, [dst_port_id], enable_port_by_unblock_queue=False)
+        if asic_type == 'cisco-8000':
+            out, err, ret = self.exec_cmd_on_dut(
+                self.dst_server_ip,
+                self.test_params['dut_username'],
+                self.test_params['dut_password'],
+                "show platform summary | egrep 'ASIC Count' | awk -F: '{print $2}'")
+            cmd_opt = "-n asic{}".format(self.test_params['dst_asic_index'])
+            if out[0].strip() == "1":
+                cmd_opt = ""
+            cmd = "sudo show platform npu script {} -s set_scheduler.py".format(cmd_opt)
+            out, err, ret = self.exec_cmd_on_dut(
+                self.dst_server_ip,
+                self.test_params['dut_username'],
+                self.test_params['dut_password'],
+                cmd)
+            if err and out == []:
+                raise RuntimeError("cmd({}) might have failed in the DUT. Error:{}".format(cmd, err))
+            else:
+                print("Success in setting scheduler in DUT.", file=sys.stderr)
+        else:
+            # Release port
+            self.sai_thrift_port_tx_enable(
+                self.dst_client,
+                asic_type,
+                [dst_port_id],
+                enable_port_by_unblock_queue=False)
 
         cnt = 0
         pkts = []
@@ -3844,6 +3868,14 @@ def runTest(self):
                 # Ignore captured non-IP packet
                 continue
 
+        if asic_type == 'cisco-8000':
+            # Release port
+            self.sai_thrift_port_tx_enable(
+                self.dst_client,
+                asic_type,
+                [dst_port_id],
+                enable_port_by_unblock_queue=False)
+
         queue_pkt_counters = [0] * (max(prio_list) + 1)
         queue_num_of_pkts = [0] * (max(prio_list) + 1)
         for prio, q_cnt in zip(prio_list, q_pkt_cnt):