Memory performance counters data size on Windows 2000 and Windows XP (262330)

SUMMARY

On Microsoft Windows 2000 and Microsoft Windows XP, the data size of some of the performance counters in Memory Performance Object has been increased to 64-bit LARGE_INTEGER. This article explains the memory performance counters that have been changed.

MORE INFORMATION

On computers that are running Microsoft Windows NT 4.0 and earlier systems, the data size of the performance counters in Memory Performance Object is defined as a 32-bit DWORD value. As a result, the counters represented in bytes can store value correctly only up to a maximum of 4 gigabytes (GB). If the actual value is more than 4 GB, the resultant performance counter will be equal to the actual value modulo 4 GB.

On Windows 2000 and Windows XP, the data size of the following performance counters in Memory Performance Object has been increased to 64-bit LARGE_INTEGER:

Available Bytes
Committed Bytes
Commit Limit
Pool Paged Bytes
Pool Nonpaged Bytes
Cache Bytes
Cache Bytes Peak
Pool Paged Resident Bytes
System Code Total Bytes
System Code Resident Bytes
System Driver Total Bytes
System Driver Resident Bytes
System Cache Resident Bytes

For these performance counters, the corresponding CounterType member in PERF_COUNTER_DEFINITION has the PERF_SIZE_LARGE flag set to indicate that the counter data is a 64-bit Large Integer.