typedef struct 
{
     ULONG Revision;
     UCHAR MaxThrottle;
     UCHAR MinThrottle;
     UCHAR BusyAdjThreshold;
     union
     {
          UCHAR Spare;
          BYTE Flags;
     };
     ULONG TimeCheck;
     ULONG IncreaseTime;
     ULONG DecreaseTime;
     ULONG IncreasePercent;
     ULONG DecreasePercent;
} PROCESSOR_PERFSTATE_POLICY, *PPROCESSOR_PERFSTATE_POLICY;

Windows Vista Kernel Structures