Set appropriate alpha values so that traffic loop can build

Summary:
The previous alpha value of 1/128 or 1/64 is too small for traffic to build on TH3/TH4 (see P1694647898 and P1694630782). Set it to 1/2 to match production settings.

Also added a small delay between pumpTraffic() and validate() calls, to make sure traffic is actually looping.

Reviewed By: nivinl

Differential Revision: D67075312

fbshipit-source-id: 9220b2323f5447fa719d4d66d12031e921c442bc

fboss/agent/test/agent_hw_tests/AgentTrafficPfcTests.cpp

@@ -264,6 +264,21 @@ class AgentTrafficPfcTest : public AgentHwTest {
   }
 
  protected:
+  cfg::MMUScalingFactor getDefaultMmuScalingFactor() {
+    auto asicType =
+        utility::checkSameAndGetAsic(getAgentEnsemble()->getL3Asics())
+            ->getAsicType();
+    switch (asicType) {
+      case cfg::AsicType::ASIC_TYPE_TOMAHAWK3:
+      case cfg::AsicType::ASIC_TYPE_TOMAHAWK4:
+      case cfg::AsicType::ASIC_TYPE_TOMAHAWK5:
+        return cfg::MMUScalingFactor::ONE_HALF;
+
+      default:
+        return cfg::MMUScalingFactor::ONE_128TH;
+    }
+  }
+
   void setupEcmpTraffic(const std::vector<PortID>& portIds) {
     utility::EcmpSetupTargetedPorts6 ecmpHelper{
         getProgrammedState(), getIntfMac()};
@@ -393,8 +408,8 @@ class AgentTrafficPfcTest : public AgentHwTest {
   void runTestWithCfg(
       const int trafficClass,
       const int pfcPriority,
-      const std::map<int, int>& tcToPgOverride = {},
-      TrafficTestParams testParams = TrafficTestParams{},
+      const std::map<int, int>& tcToPgOverride,
+      TrafficTestParams testParams,
       std::function<void(
           AgentEnsemble* ensemble,
           const int pri,
@@ -410,6 +425,9 @@ class AgentTrafficPfcTest : public AgentHwTest {
         // Apply PFC config to all ports
         portIdsToConfigure = masterLogicalInterfacePortIds();
       }
+      if (!testParams.buffer.scalingFactor.has_value()) {
+        testParams.buffer.scalingFactor = getDefaultMmuScalingFactor();
+      }
       utility::setupPfcBuffers(
           getAgentEnsemble(),
           cfg,
@@ -448,6 +466,10 @@ class AgentTrafficPfcTest : public AgentHwTest {
     };
     auto verifyCommon = [&](bool postWb) {
       pumpTraffic(trafficClass);
+      // Sleep for a bit before validation, so that the test will fail if
+      // traffic doesn't actually build up, instead of passing by luck.
+      // NOLINTNEXTLINE(facebook-hte-BadCall-sleep)
+      sleep(2);
       // check counters are as expected
       validateCounterFn(getAgentEnsemble(), pfcPriority, portIds);
       if (testParams.expectDrop) {
@@ -493,15 +515,11 @@ INSTANTIATE_TEST_SUITE_P(
             .scale = true},
         TrafficTestParams{
             .name = "WithZeroPgHeadRoomCfg",
-            .buffer =
-                PfcBufferParams{.pgHeadroom = 0, .scalingFactor = std::nullopt},
+            .buffer = PfcBufferParams{.pgHeadroom = 0},
             .expectDrop = true},
         TrafficTestParams{
             .name = "WithZeroGlobalHeadRoomCfg",
-            .buffer =
-                PfcBufferParams{
-                    .globalHeadroom = 0,
-                    .scalingFactor = std::nullopt},
+            .buffer = PfcBufferParams{.globalHeadroom = 0},
             .expectDrop = true}),
     [](const ::testing::TestParamInfo<TrafficTestParams>& info) {
       return info.param.name;
@@ -528,7 +546,11 @@ TEST_P(AgentTrafficPfcGenTest, verifyPfc) {
 TEST_F(AgentTrafficPfcTest, verifyPfcWithMapChanges_0) {
   const int trafficClass = kLosslessTrafficClass;
   const int pfcPriority = 3;
-  runTestWithCfg(trafficClass, pfcPriority, {{trafficClass, pfcPriority}});
+  runTestWithCfg(
+      trafficClass,
+      pfcPriority,
+      {{trafficClass, pfcPriority}},
+      TrafficTestParams{});
 }
 
 // intent of this test is to send traffic so that it maps to
@@ -538,19 +560,21 @@ TEST_F(AgentTrafficPfcTest, verifyPfcWithMapChanges_0) {
 TEST_F(AgentTrafficPfcTest, verifyPfcWithMapChanges_1) {
   const int trafficClass = 7;
   const int pfcPriority = kLosslessPriority;
-  runTestWithCfg(trafficClass, pfcPriority, {{trafficClass, pfcPriority}});
+  runTestWithCfg(
+      trafficClass,
+      pfcPriority,
+      {{trafficClass, pfcPriority}},
+      TrafficTestParams{});
 }
 
 TEST_F(AgentTrafficPfcTest, verifyBufferPoolWatermarks) {
   const int trafficClass = kLosslessTrafficClass;
   const int pfcPriority = kLosslessPriority;
-  cfg::MMUScalingFactor scalingFactor = cfg::MMUScalingFactor::ONE_64TH;
   runTestWithCfg(
       trafficClass,
       pfcPriority,
       {},
-      TrafficTestParams{
-          .buffer = PfcBufferParams{.scalingFactor = scalingFactor}},
+      TrafficTestParams{},
       validateBufferPoolWatermarkCounters);
 }
 
@@ -561,8 +585,7 @@ TEST_F(AgentTrafficPfcTest, verifyIngressPriorityGroupWatermarks) {
       trafficClass,
       pfcPriority,
       {},
-      TrafficTestParams{
-          .buffer = PfcBufferParams{.scalingFactor = std::nullopt}},
+      TrafficTestParams{},
       validateIngressPriorityGroupWatermarkCounters);
 }
 
@@ -576,7 +599,7 @@ class AgentTrafficPfcWatchdogTest : public AgentTrafficPfcTest {
         portIds,
         kLosslessPgIds,
         {},
-        PfcBufferParams{});
+        PfcBufferParams{.scalingFactor = cfg::MMUScalingFactor::ONE_128TH});
     applyNewConfig(cfg);
     setupEcmpTraffic(portIds);
   }

fboss/agent/test/utils/PfcTestUtils.h

@@ -5,7 +5,7 @@
 #include "fboss/agent/Utils.h"
 #include "fboss/agent/gen-cpp2/switch_config_types.h"
 #include "fboss/agent/hw/gen-cpp2/hardware_stats_types.h"
-#include "fboss/agent/test/AgentHwTest.h"
+#include "fboss/agent/test/AgentEnsemble.h"
 
 namespace facebook::fboss::utility {
 
@@ -14,8 +14,7 @@ struct PfcBufferParams {
   int globalHeadroom = 5000; // keep this lower than globalShared
   int pgLimit = 2200;
   int pgHeadroom = 2200; // keep this lower than globalShared
-  std::optional<facebook::fboss::cfg::MMUScalingFactor> scalingFactor =
-      facebook::fboss::cfg::MMUScalingFactor::ONE_128TH;
+  std::optional<facebook::fboss::cfg::MMUScalingFactor> scalingFactor;
   int resumeOffset = 1800;
 };