Evaluating Memory and Cache Usage

Kernel-mode processes, such as device drivers, can also leak memory when bytes are allocated but not freed. Again, you typically track these over a period of several hours or days, but instead of relying on System Monitor counters, use Pool Monitor (Poolmon.exe). For information about Pool Monitor, see Windows 2000 Support Tools Help. For information about installing and using the Windows 2000 Support Tools and Support Tools Help, see the file Sreadme.doc in the \Support\Tools folder of the Windows 2000 operating system CD.

Pool Monitor (Poolmon.exe) shows the amounts of nonpaged and paged memory that were allocated and freed, calculates the difference between these, and associates the data with a function tag to help you identify the process involved. By default, Windows 2000 is configured not to collect pool information because of the overhead. To use Poolmon, you must enable the pool tag signal. Use Gflags.exe to make the change. In Gflags, select the Enable Pool Tag check box. For information about using Poolmon and Gflags, see Support Tools Help. For information about installing and using the Windows 2000 Support Tools and Support Tools Help, see the file Sreadme.doc in the \Support\Tools folder of the Windows 2000 operating system CD.

The pool tag is a mechanism for identifying the driver or other part of the kernel allocated to a particular portion of memory. These tags can be examined to reveal memory leaks and pool corruption, and the offending code component can be determined by finding which code component is allocated to which tag. Look for a tag with rapidly increasing byte counts that does not free as many bytes as it allocates, and verify that this tag corresponds to a function for which the increasing memory allocation might be appropriate. If it does not appear appropriate, it might be necessary to debug and tune the application to eliminate the leak.

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