The !defwrites extension displays the values of the kernel variables used by the cache manager.



Windows 2000


Windows XP and later


Additional Information

For information about write throttling, see Microsoft Windows Internals by Mark Russinovich and David Solomon. (This book may not be available in some languages and countries.)

For information about other cache management extensions, use the !cchelp extension.


When the number of deferred writes ("dirty pages") becomes too large, page writing will be throttled. This extension allows you to see whether your system has reached this point.

Here is an example:

kd> !defwrites 
*** Cache Write Throttle Analysis ***

        CcTotalDirtyPages:                   0 (       0 Kb)
        CcDirtyPageThreshold:             1538 (    6152 Kb)
        MmAvailablePages:                 2598 (   10392 Kb)
        MmThrottleTop:                     250 (    1000 Kb)
        MmThrottleBottom:                   30 (     120 Kb)
        MmModifiedPageListHead.Total:      699 (    2796 Kb)

Write throttles not engaged

In this case, there are no dirty pages. If CcTotalDirtyPages reaches 1538 (the value of CcDirtyPageThreshold), writing will be delayed until the number of dirty pages is reduced.