Fix affinity bonus normalization in placement scoring

cursoragent · cursoragent · commit 878be92bc5e5 · 2026-05-30T23:39:13.000Z
Normalize the affinity bonus by dividing it by totalCapacity to ensure
the relative impact of the bonus is consistent across nodes of different
sizes. Without normalization, the absolute affinity bonus has a
disproportionately stronger effect on large nodes (where the base score
is smaller) compared to small nodes, causing the algorithm to strongly
prefer large nodes with cache affinity even when smaller nodes are less
loaded.
diff --git a/packages/api/internal/orchestrator/placement/placement_best_of_K.go b/packages/api/internal/orchestrator/placement/placement_best_of_K.go
@@ -63,7 +63,7 @@ func (b *BestOfK) Score(node *nodemanager.Node, resources nodemanager.SandboxRes
 
 	score := (cpuRequested + float64(reserved) + config.Alpha*usageAvg) / totalCapacity
 	if len(affinityScores) > 0 {
-		score -= affinityScores[0][node.ID]
+		score -= affinityScores[0][node.ID] / totalCapacity
 	}
 
 	return score

Original file line number	Diff line number	Diff line change
`@@ -63,7 +63,7 @@ func (b BestOfK) Score(node nodemanager.Node, resources nodemanager.SandboxRes`
`63`	`63`
`64`	`64`	`score := (cpuRequested + float64(reserved) + config.Alpha*usageAvg) / totalCapacity`
`65`	`65`	`if len(affinityScores) > 0 {`
`66`		`- score -= affinityScores[0][node.ID]`
	`66`	`+ score -= affinityScores[0][node.ID] / totalCapacity`
`67`	`67`	`}`
`68`	`68`
`69`	`69`	`return score`