Add benchmark fan duty cycle summary to report

audit/internal/platform/benchmark.go

@@ -401,6 +401,7 @@ func (s *System) RunNvidiaBenchmark(ctx context.Context, baseDir string, opts Nv
 		serverLoadedW = serverLoadedWSum / float64(serverLoadedSamples)
 	}
 	result.ServerPower = characterizeServerPower(serverIdleW, serverLoadedW, gpuReportedSumW, serverIdleOK && serverLoadedOK)
+	result.Cooling = summarizeBenchmarkCooling(metricRows)
 
 	// Apply server-power penalty when IPMI reports the server delta is much
 	// lower than GPU-reported sum: GPU power telemetry is over-stated, making
@@ -739,7 +740,7 @@ func collectBenchmarkSamples(ctx context.Context, durationSec int, gpuIndices []
 		if ctx.Err() != nil {
 			return rows, ctx.Err()
 		}
-		samples, err := sampleGPUMetrics(gpuIndices)
+		samples, err := sampleBenchmarkTelemetry(gpuIndices)
 		if err == nil {
 			elapsed := time.Since(start).Seconds()
 			for i := range samples {
@@ -774,7 +775,7 @@ func runBenchmarkCommandWithMetrics(ctx context.Context, verboseLog, name string
 			case <-stopCh:
 				return
 			case <-ticker.C:
-				samples, err := sampleGPUMetrics(gpuIndices)
+				samples, err := sampleBenchmarkTelemetry(gpuIndices)
 				if err != nil {
 					continue
 				}
@@ -794,6 +795,37 @@ func runBenchmarkCommandWithMetrics(ctx context.Context, verboseLog, name string
 	return out, metricRows, err
 }
 
+type benchmarkCoolingSample struct {
+	AvgFanRPM             float64
+	AvgFanDutyCyclePct    float64
+	FanDutyCycleAvailable bool
+}
+
+func sampleBenchmarkTelemetry(gpuIndices []int) ([]GPUMetricRow, error) {
+	samples, err := sampleGPUMetrics(gpuIndices)
+	if err != nil {
+		return nil, err
+	}
+	fanSample := sampleBenchmarkCoolingSample()
+	for i := range samples {
+		samples[i].FanAvgRPM = fanSample.AvgFanRPM
+		samples[i].FanDutyCyclePct = fanSample.AvgFanDutyCyclePct
+		samples[i].FanDutyCycleAvailable = fanSample.FanDutyCycleAvailable
+	}
+	return samples, nil
+}
+
+func sampleBenchmarkCoolingSample() benchmarkCoolingSample {
+	fans, _ := sampleFanSpeeds()
+	avgRPM, _, _ := fanRPMStats(fans)
+	dutyPct, dutyAvailable := sampleFanDutyCyclePct()
+	return benchmarkCoolingSample{
+		AvgFanRPM:             avgRPM,
+		AvgFanDutyCyclePct:    dutyPct,
+		FanDutyCycleAvailable: dutyAvailable,
+	}
+}
+
 func annotateBenchmarkMetricRows(rows []GPUMetricRow, stage string, offset float64) []GPUMetricRow {
 	if len(rows) == 0 {
 		return nil
@@ -1022,6 +1054,37 @@ func summarizeBenchmarkTelemetry(rows []GPUMetricRow) BenchmarkTelemetrySummary
 	return summary
 }
 
+func summarizeBenchmarkCooling(rows []GPUMetricRow) *BenchmarkCoolingSummary {
+	if len(rows) == 0 {
+		return nil
+	}
+	var rpmValues []float64
+	var dutyValues []float64
+	for _, row := range rows {
+		if row.FanAvgRPM > 0 {
+			rpmValues = append(rpmValues, row.FanAvgRPM)
+		}
+		if row.FanDutyCycleAvailable {
+			dutyValues = append(dutyValues, row.FanDutyCyclePct)
+		}
+	}
+	if len(rpmValues) == 0 && len(dutyValues) == 0 {
+		return nil
+	}
+	summary := &BenchmarkCoolingSummary{
+		Available: true,
+		AvgFanRPM: benchmarkMean(rpmValues),
+	}
+	if len(dutyValues) > 0 {
+		summary.FanDutyCycleAvailable = true
+		summary.AvgFanDutyCyclePct = benchmarkMean(dutyValues)
+		summary.P95FanDutyCyclePct = benchmarkPercentile(dutyValues, 95)
+	} else {
+		summary.Notes = append(summary.Notes, "fan duty cycle unavailable on this host; RPM-only fan telemetry was collected")
+	}
+	return summary
+}
+
 func scoreBenchmarkGPUResult(gpu BenchmarkGPUResult) BenchmarkScorecard {
 	score := BenchmarkScorecard{}