The !memusage extension displays summary statistics about physical memory use.


!memusage [Flags]


Can be any one of the following values. The default is 0x0.

Displays general summary information, along with a more detailed description of the pages in the PFN database. See the Remarks section for an example of this type of output.

Displays only summary information about the modified no-write pages in the PFN database.

Displays only detailed information about the modified no-write pages in the PFN database.

Displays only general summary information about memory use.


Modes: kernel mode only



Additional Information

Physical memory statistics are collected from the Memory Manager's page frame number (PFN) database table.

This command takes a long time to run, especially if the target computer is running in 64-bit mode, due to the greater amount of data to obtain. While it is loading the PFN database, a counter shows its progress. To speed up this loading, use a network connection, or increase the COM port speed with the CTRL+A (Toggle Baud Rate) key, or use the .cache (Set Cache Size) command to increase the cache size (perhaps to around 10 MB).

The !memusage command can also be used while performing local kernel debugging.

Here is an example of the output from this extension:

kd> !memusage
loading PFN database
loading (100% complete)
Compiling memory usage data (99% Complete).
             Zeroed:      218 (     872 kb)
               Free:      831 (    3324 kb)
            Standby:   124049 (  496196 kb)
           Modified:    55101 (  220404 kb)
    ModifiedNoWrite:       58 (     232 kb)
       Active/Valid:   321846 ( 1287384 kb)
         Transition:        8 (      32 kb)
         SLIST/Temp:     1533 (    6132 kb)
                Bad:        0 (       0 kb)
            Unknown:        0 (       0 kb)
              TOTAL:   503644 ( 2014576 kb)

Dangling Yes Commit:      184 (     736 kb)
 Dangling No Commit:    81706 (  326824 kb)
  Building kernel map
  Finished building kernel map
Scanning PFN database - (100% complete) 


Also included in the report is detailed information about the usage of memory that is visible to the debugger.

  Usage Summary (in Kb):
Control       Valid Standby Dirty Shared Locked PageTables  name
ffffaf0fb369f010   204    956     0    32   204     0  mapped_file( shell32.dll )
ffffaf0fb369f270   492     60     0   252   492     0  mapped_file( KernelBase.dll )
ffffaf0fb36ad050    20     36     0     0    20     0  mapped_file( WMIsvc.dll )
ffffaf0fb36adad0    88    144     0    40    88     0  mapped_file( Can't read file name buffer at ffffc10e0497e170 )
ffffaf0fb36b5670   780   1012     0   560   780     0  mapped_file( KernelBase.dll )
ffffaf0fb36b5910    44    144     0    28    44     0  mapped_file( cfgmgr32.dll )
ffffaf0fb36bc270     8      0     0     0     8     0  mapped_file( Can't read file name buffer at ffffc10e061a17d0 )
ffffaf0fb36bc520    24     56     0     4    24     0  mapped_file( ShareHost.dll )


The first column displays the address of the control area structure that describes each mapped structure. Use the !ca extension command to display these control areas.


You can use the !vm extension command to analyze virtual memory use. This extension is typically more useful than !memusage. For more information about memory management, see Microsoft Windows Internals, by Pavel Yosifovich, Andrea Allievi, Alex Ionescu, Mark Russinovich and David Solomon.

The !pfn extension command can be used to display a particular page frame entry in the PFN database.

The !pool extension displays information about a specific pool allocation or about the entire system-wide pool.