From 2cdf034bb0abfcd9eee7bbdef4301ec2c8b6b8b8 Mon Sep 17 00:00:00 2001
From: Michael Chus <mike@mchus.pro>
Date: Sun, 19 Apr 2026 18:43:36 +0300
Subject: [PATCH] Use SDR PSU AC input for per-step server power in power ramp

When sdrStep.PSUInW is available, prefer it over DCMI for
ramp.ServerLoadedW and ServerDeltaW. DCMI on this platform (MSI 4-PSU)
reports ~half actual draw; SDR sums all PSU_POWER_IN sensors correctly.

Delta is now SDR-to-SDR (sdrStep.PSUInW - sdrIdle.PSUInW) for
consistency. DCMI path kept as fallback when SDR has no PSU data.
Log message now indicates the source (SDR PSU AC input vs DCMI).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 audit/internal/platform/benchmark.go | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/audit/internal/platform/benchmark.go b/audit/internal/platform/benchmark.go
index 7a1b991..630bc83 100644
--- a/audit/internal/platform/benchmark.go
+++ b/audit/internal/platform/benchmark.go
@@ -4346,7 +4346,6 @@ func (s *System) RunNvidiaPowerBench(ctx context.Context, baseDir string, opts N
 		if w, ok := <-ipmiStepDone; ok {
 			stepIPMILoadedW = w
 			stepIPMIOK = true
-			logFunc(fmt.Sprintf("power ramp: step %d IPMI loaded: %.0f W", step, w))
 		}
 		// Accumulate restore actions; they all run in the outer defer.
 		allRestoreActions = append(allRestoreActions, stepRestore...)
@@ -4410,9 +4409,27 @@ func (s *System) RunNvidiaPowerBench(ctx context.Context, baseDir string, opts N
 			result.Findings = append(result.Findings, fmt.Sprintf("Ramp step %d (GPU %d) required derating to %.0f W under combined thermal load.", step, newGPUIdx, c.AppliedPowerLimitW))
 		}
 
-		if stepIPMIOK && serverIdleOK && stepIPMILoadedW > 0 {
+		// Per-step PSU slot snapshot — also used as the authoritative loaded power
+		// source when SDR PSU sensors are available (more accurate than DCMI on
+		// servers where DCMI covers only a subset of installed PSUs).
+		sdrStep := sampleIPMISDRPowerSensors()
+		if len(sdrStep.PSUSlots) > 0 {
+			ramp.PSUSlotReadings = sdrStep.PSUSlots
+		}
+
+		if sdrStep.PSUInW > 0 {
+			// SDR PSU sum is available — use it for server power (includes all PSUs).
+			ramp.ServerLoadedW = sdrStep.PSUInW
+			ramp.ServerDeltaW = sdrStep.PSUInW - sdrIdle.PSUInW
+			logFunc(fmt.Sprintf("power ramp: step %d IPMI loaded: %.0f W (SDR PSU AC input)", step, sdrStep.PSUInW))
+			if step == len(result.RecommendedSlotOrder) {
+				serverLoadedW = sdrStep.PSUInW
+				serverLoadedOK = true
+			}
+		} else if stepIPMIOK && serverIdleOK && stepIPMILoadedW > 0 {
 			ramp.ServerLoadedW = stepIPMILoadedW
 			ramp.ServerDeltaW = stepIPMILoadedW - serverIdleW
+			logFunc(fmt.Sprintf("power ramp: step %d IPMI loaded: %.0f W (DCMI)", step, stepIPMILoadedW))
 			// The last step has all GPUs loaded — use it as the top-level loaded_w.
 			if step == len(result.RecommendedSlotOrder) {
 				serverLoadedW = stepIPMILoadedW
@@ -4420,12 +4437,6 @@ func (s *System) RunNvidiaPowerBench(ctx context.Context, baseDir string, opts N
 			}
 		}
 
-		// Per-step PSU slot snapshot.
-		sdrStep := sampleIPMISDRPowerSensors()
-		if len(sdrStep.PSUSlots) > 0 {
-			ramp.PSUSlotReadings = sdrStep.PSUSlots
-		}
-
 		// Fan state at end of ramp step.
 		if fans, err := sampleFanSpeeds(); err == nil && len(fans) > 0 {
 			ramp.AvgFanRPM = meanFanRPM(fans)