using required number of cores for picking best recommendation

yb-voyager/src/migassessment/sizing.go

@@ -103,6 +103,7 @@ type IntermediateRecommendation struct {
 	EstimatedTimeInMinForImport     float64
 	ParallelVoyagerJobs             float64
 	FailureReasoning                string
+	CoresNeeded                     float64
 }
 
 const (
@@ -301,13 +302,11 @@ func pickBestRecommendation(recommendation map[int]IntermediateRecommendation) I
 		if rec.FailureReasoning == "" {
 			foundRecommendation = true
 			// Update finalRecommendation if the current recommendation has fewer cores.
-			// Buffer to choose setup with higher vCPU if difference between required cores between two setup is less
-			// than higher vCPU count.
-			if minCores > int(rec.NumNodes)*rec.VCPUsPerInstance &&
-				(minCores-int(rec.NumNodes)*rec.VCPUsPerInstance) > finalRecommendation.VCPUsPerInstance {
+			log.Infof(fmt.Sprintf("vCPU: %v & cores required: %v gives nodes required: %v\n", rec.VCPUsPerInstance, rec.CoresNeeded, rec.NumNodes))
+			if minCores > int(rec.CoresNeeded) {
 				finalRecommendation = rec
-				minCores = int(rec.NumNodes) * rec.VCPUsPerInstance
-			} else if minCores == int(rec.NumNodes)*rec.VCPUsPerInstance {
+				minCores = int(rec.CoresNeeded)
+			} else if minCores == int(rec.CoresNeeded) {
 				// If the number of cores is the same across machines, recommend the machine with higher core count
 				if rec.VCPUsPerInstance > finalRecommendation.VCPUsPerInstance {
 					finalRecommendation = rec
@@ -383,6 +382,7 @@ func findNumNodesNeededBasedOnThroughputRequirement(sourceIndexMetadata []Source
 			ShardedSize:                     previousRecommendation.ShardedSize,
 			EstimatedTimeInMinForImport:     previousRecommendation.EstimatedTimeInMinForImport,
 			FailureReasoning:                previousRecommendation.FailureReasoning,
+			CoresNeeded:                     neededCores,
 		}
 	}
 	// Return updated recommendation map
@@ -431,7 +431,9 @@ func findNumNodesNeededBasedOnTabletsRequired(sourceIndexMetadata []SourceDBMeta
 					// update recommendation to use the maximum of the existing recommended nodes and nodes calculated based on tablets
 					// Caveat: if new nodes required is more than the existing recommended nodes, we would need to
 					// re-evaluate tablets required. Although, in this iteration we've skipping re-evaluation.
-					rec.NumNodes = math.Max(rec.NumNodes, nodesRequired)
+					currentMaxRequiredNodes := math.Max(nodesRequired, rec.NumNodes)
+					rec.CoresNeeded = lo.Ternary(nodesRequired <= rec.NumNodes, rec.CoresNeeded, currentMaxRequiredNodes*float64(rec.VCPUsPerInstance))
+					rec.NumNodes = currentMaxRequiredNodes
 					recommendation[i] = rec
 				}
 			}

yb-voyager/src/migassessment/sizing_test.go

@@ -1,5 +1,3 @@
-//go:build unit
-
 /*
 Copyright (c) YugabyteDB, Inc.
 
@@ -777,6 +775,7 @@ func TestFindNumNodesNeededBasedOnTabletsRequired_CanSupportTablets(t *testing.T
 			},
 			VCPUsPerInstance: 4,
 			NumNodes:         3,
+			CoresNeeded:      10,
 		},
 	}
 
@@ -786,6 +785,7 @@ func TestFindNumNodesNeededBasedOnTabletsRequired_CanSupportTablets(t *testing.T
 
 	// check if the num nodes in updated recommendation is same as before(3) meaning no scaling is required
 	assert.Equal(t, float64(3), updatedRecommendation[4].NumNodes)
+	assert.Equal(t, float64(10), updatedRecommendation[4].CoresNeeded)
 }
 
 // validate that the tablets cannot be supported by existing nodes and scaling is needed
@@ -816,15 +816,17 @@ func TestFindNumNodesNeededBasedOnTabletsRequired_NeedMoreNodes(t *testing.T) {
 			},
 			VCPUsPerInstance: 4,
 			NumNodes:         3,
+			CoresNeeded:      10,
 		},
 	}
 
 	// Run the function
 	updatedRecommendation :=
 		findNumNodesNeededBasedOnTabletsRequired(sourceIndexMetadata, shardedLimits, recommendation)
 
-	// check if the num nodes in updated recommendation has increased. Meaning scaling is required.
+	// check if the num nodes and cores in updated recommendation has increased. Meaning scaling is required.
 	assert.Equal(t, float64(6), updatedRecommendation[4].NumNodes)
+	assert.Equal(t, float64(24), updatedRecommendation[4].CoresNeeded)
 }
 
 /*
@@ -836,11 +838,13 @@ func TestPickBestRecommendation_PickOneWithOptimalNodesAndCores(t *testing.T) {
 		4: {
 			VCPUsPerInstance: 4,
 			NumNodes:         10,
+			CoresNeeded:      40,
 			FailureReasoning: "",
 		},
 		8: {
 			VCPUsPerInstance: 8,
 			NumNodes:         3,
+			CoresNeeded:      24,
 			FailureReasoning: "",
 		},
 	}
@@ -855,16 +859,19 @@ func TestPickBestRecommendation_PickOneWithOptimalNodesAndCoresWhenSomeHasFailur
 		4: {
 			VCPUsPerInstance: 4,
 			NumNodes:         10,
+			CoresNeeded:      40,
 			FailureReasoning: "has some failure",
 		},
 		8: {
 			VCPUsPerInstance: 8,
 			NumNodes:         3,
+			CoresNeeded:      24,
 			FailureReasoning: "has some failure as well",
 		},
 		16: {
 			VCPUsPerInstance: 16,
 			NumNodes:         3,
+			CoresNeeded:      48,
 			FailureReasoning: "",
 		},
 	}
@@ -897,6 +904,54 @@ func TestPickBestRecommendation_PickLastMaxCoreRecommendationWhenNoneCanSupport(
 	assert.Equal(t, 16, bestPick.VCPUsPerInstance)
 }
 
+// validate if the recommendation with min required cores is used.
+func TestPickBestRecommendation_PickRecommendationWithMinCoresRequired(t *testing.T) {
+	recommendations := map[int]IntermediateRecommendation{
+		4: {
+			VCPUsPerInstance: 4,
+			NumNodes:         83,
+			CoresNeeded:      329,
+		},
+		8: {
+			VCPUsPerInstance: 8,
+			NumNodes:         37,
+			CoresNeeded:      296,
+		},
+		16: {
+			VCPUsPerInstance: 16,
+			NumNodes:         19,
+			CoresNeeded:      290,
+		},
+	}
+	bestPick := pickBestRecommendation(recommendations)
+	// validate the best recommendation which is 16 vcpus per instance is picked up
+	assert.Equal(t, 16, bestPick.VCPUsPerInstance)
+}
+
+// validate if the recommendation with higher vCPU is selected if required cores are same.
+func TestPickBestRecommendation_PickHigherVCPURecommendationWhenSameCoresRequired(t *testing.T) {
+	recommendations := map[int]IntermediateRecommendation{
+		4: {
+			VCPUsPerInstance: 4,
+			NumNodes:         12,
+			CoresNeeded:      48,
+		},
+		8: {
+			VCPUsPerInstance: 8,
+			NumNodes:         6,
+			CoresNeeded:      48,
+		},
+		16: {
+			VCPUsPerInstance: 16,
+			NumNodes:         3,
+			CoresNeeded:      48,
+		},
+	}
+	bestPick := pickBestRecommendation(recommendations)
+	// validate the best recommendation which is 16 vcpus per instance is picked up
+	assert.Equal(t, 16, bestPick.VCPUsPerInstance)
+}
+
 /*
 ===== 	Test functions to test calculateTimeTakenAndParallelJobsForImport function	=====
 */