fix: Interpret negative or 0 half life values as disabled (#831)

* Interpret negative or 0 half life values as disabled

Author: itsomri

CHANGELOG.md

@@ -18,6 +18,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - Fixed pod controller logging to use request namespace/name instead of empty pod object fields when pod is not found
 - Fixed a bug where topology constrains with equal required and preferred levels would cause preferred level not to be found.
 - Fixed GPU memory pods Fair Share and Queue Order calculations
+- Interpret negative or zero half-life value as disabled [#818](https://github.com/NVIDIA/KAI-Scheduler/pull/818) [itsomri](https://github.com/itsomri)
 
 ## [v0.12.0] - 2025-12-24
 

pkg/scheduler/cache/usagedb/api/defaults.go

@@ -13,6 +13,9 @@ func (p *UsageParams) SetDefaults() {
 	if p.HalfLifePeriod == nil {
 		// noop: disabled by default
 	}
+	if p.HalfLifePeriod != nil && p.HalfLifePeriod.Duration <= 0 {
+		p.HalfLifePeriod = nil
+	}
 	if p.WindowSize == nil {
 		p.WindowSize = &metav1.Duration{Duration: time.Hour * 24 * 7}
 	}

pkg/scheduler/cache/usagedb/api/usage_params_test.go

@@ -27,6 +27,28 @@ func TestUsageParams_SetDefaults(t *testing.T) {
 				WindowType:     &[]WindowType{SlidingWindow}[0],
 			},
 		},
+		{
+			name: "negative half life period should be disabled",
+			input: &UsageParams{
+				HalfLifePeriod: &metav1.Duration{Duration: -3 * time.Minute},
+			},
+			expected: &UsageParams{
+				HalfLifePeriod: nil,
+				WindowSize:     &metav1.Duration{Duration: time.Hour * 24 * 7},
+				WindowType:     &[]WindowType{SlidingWindow}[0],
+			},
+		},
+		{
+			name: "zero half life period should be disabled",
+			input: &UsageParams{
+				HalfLifePeriod: &metav1.Duration{Duration: 0 * time.Minute},
+			},
+			expected: &UsageParams{
+				HalfLifePeriod: nil,
+				WindowSize:     &metav1.Duration{Duration: time.Hour * 24 * 7},
+				WindowType:     &[]WindowType{SlidingWindow}[0],
+			},
+		},
 		{
 			name: "params with half life set should preserve it",
 			input: &UsageParams{
@@ -290,10 +312,9 @@ func TestUsageParams_ZeroValues(t *testing.T) {
 
 	params.SetDefaults()
 
-	// Zero values should be preserved, not replaced with defaults
-	require.NotNil(t, params.HalfLifePeriod)
-	assert.Equal(t, time.Duration(0), params.HalfLifePeriod.Duration)
+	require.Nil(t, params.HalfLifePeriod)
 
+	// Zero values should be preserved, not replaced with defaults
 	require.NotNil(t, params.WindowSize)
 	assert.Equal(t, time.Duration(0), params.WindowSize.Duration)