Fix incorrect CPU utilization statistics on Windows 11 22H2 and newer

Author: Kaldaien

IntelPresentMon/ControlLib/WmiCpu.cpp

@@ -9,7 +9,7 @@ std::wstring kProcessorFrequency =
     L"\\Processor Information(_Total)\\Processor Frequency";
 std::wstring kProcessorPerformance =
     L"\\Processor Information(_Total)\\% Processor Performance";
-std::wstring kProcessorTime = L"\\Processor(_Total)\\% Processor Time";
+std::wstring kProcessorIdleTime = L"\\Processor(_Total)\\% Idle Time";
 
 WmiCpu::WmiCpu() {
   HQUERY temp_query = nullptr;
@@ -119,13 +119,24 @@ bool WmiCpu::Sample() noexcept {
     }
   }
 
-  // Sample cpu utilization
+  // Sample cpu idle time, and compute cpu utilization using it (Windows 11 Fix)
+  //
+  // Beginning with Windows 11 22H2, the performance counters for CPU idle time
+  // in SystemProcessorPerformanceInformation are broken and statistics derived
+  // from those counters will always indicate single-digit cpu utilization %.
+  //
+  // Idle time reported in SystemProcessorIdleInformation is still consistent on
+  // all versions of Windows, as well as WMI provisioned "Processor\% Idle Time".
+  //
+  // To measure CPU utilization accurately on all systems, it must be calculated:
+  // 
+  //    100.0 - "Processor(_Total)\% Idle Time"
   {
     if (const auto result =
-            PdhGetFormattedCounterValue(processor_time_counter_, PDH_FMT_DOUBLE,
+            PdhGetFormattedCounterValue(processor_idle_time_counter_, PDH_FMT_DOUBLE,
                                         &counter_type, &counter_value);
         result == ERROR_SUCCESS) {
-      info.cpu_utilization = counter_value.doubleValue;
+      info.cpu_utilization = 100.0 - counter_value.doubleValue;
       SetTelemetryCapBit(CpuTelemetryCapBits::cpu_utilization);
     }
   }

IntelPresentMon/ControlLib/WmiCpu.h

@@ -30,7 +30,7 @@ class WmiCpu : public CpuTelemetry {
   std::unique_ptr<std::remove_pointer_t<PDH_HQUERY>, PDHQueryDeleter> query_;
   HCOUNTER processor_frequency_counter_;
   HCOUNTER processor_performance_counter_;
-  HCOUNTER processor_time_counter_;
+  HCOUNTER processor_idle_time_counter_;
   LARGE_INTEGER next_sample_qpc_ = {};
   LARGE_INTEGER frequency_ = {};
   std::string cpu_name_;