Performance counter value may unexpectedly leap forward (274323)

MORE INFORMATION

Design defects within a hardware chip are known as errata. These design defects may cause the product to deviate from published specifications. For information on errata in specific chipsets, please contact the hardware vendor for the chipset.

A machine's PCI components are identified by a PCI identifier within the following key in the Windows registry: The names of subkeys have the following form where xxxx:yyyy represents the PCI identifier.

Currently, chips with the following PCI identifiers are known to exhibit a jump in performance counter value:

PCI ID	Hardware Vendor
1039:0530	Silicon Integrated Systems (SiS)
1039:0620	Silicon Integrated Systems (SiS)
10B9:0533	Acer Labs, Inc. (ALi)
10B9:1533	Acer Labs, Inc. (ALi)
1106:0596	VIA Technologies, Inc. (VIA)
1106:0686	VIA Technologies, Inc. (VIA)
1166:004F	Serverworks Corporation
1166:0050	Serverworks Corporation
8086:7110	Intel Corporation

This list will be updated as Microsoft observes the behavior in other chipsets.

Sample Code

The following sample code demonstrates the method described above for detecting performance counter leaps. If the code is run on a computer with the PIIX4 chipset, for example, this console application will sporadically report leaps in the performance counter value.

#include <windows.h>
#include <stdio.h>

void main() {

   LARGE_INTEGER liFrequency;
   LARGE_INTEGER liCurrent;
   LARGE_INTEGER liLast;
   LARGE_INTEGER liRecent[10];
   DWORD dwCurrent;
   DWORD dwLast;
   DWORD dwPerfElapsed;
   DWORD dwTickElapsed;
   int i = 0;
   int j;

   // Save the performance counter frequency for later use.
   if (!QueryPerformanceFrequency(&liFrequency))
      printf("QPF() failed with error %d\n", GetLastError());

   // Query the performance counter value and tick count.
   dwCurrent = GetTickCount();
   if (!QueryPerformanceCounter(&liCurrent))
      printf("QPC() failed with error %d\n", GetLastError());

   liLast = liCurrent;
   dwLast = dwCurrent;

   while (TRUE) {

      // Query the performance counter value and tick count.
      if (!QueryPerformanceCounter(&liCurrent))
         printf("QPC() failed with error %d\n", GetLastError());
      dwCurrent = GetTickCount();

      // Store the performance counter value in the list of recent values.
      liRecent[i].QuadPart = liCurrent.QuadPart;
      i = (i+1) % 10;

      // Convert difference in performance counter values to milliseconds.
      dwPerfElapsed = (DWORD) (((liCurrent.QuadPart - liLast.QuadPart) 
            * 1000) / liFrequency.QuadPart);
      
      dwTickElapsed = dwCurrent - dwLast;

      // Check for a discrepancy greater than 500 milliseconds.
      if (abs(dwPerfElapsed - dwTickElapsed) > 500) { 

         // Print the previous 9 performance-counter values.
         for (j=9; j>0; j--) {
            printf("      Previous %d:  %I64X\n", j, liRecent[i].QuadPart);
            i = (i+1) % 10;
         }

         // Print the leap value.
         printf( "LEAP: Current:     %I64X  delta = %I64X\n", 
               liCurrent.QuadPart, liCurrent.QuadPart - liLast.QuadPart);
         
         // Retrieve and print the next 9 performance-counter values.
         for (j=1; j<=9; j++) {
            
            QueryPerformanceCounter(&liCurrent);
            printf("      Next     %d:  %I64X\n", j, liCurrent.QuadPart);
            
            liRecent[i].QuadPart = liCurrent.QuadPart;
            i = (i+1) % 10;
         }

         printf("\n");
      }

      liLast = liCurrent;
      dwLast = dwCurrent;
   }

   return;
}