The !lookaside extension displays information about look-aside lists, resets the counters of look-aside lists, or modifies the depth of a look-aside list.

!lookaside [Address [Options [Depth]]]
!lookaside [-all]
!lookaside 0 [-all]


Specifies the hexadecimal address of a look-aside list to be displayed or modified.

If Address is omitted (or 0) and the -all option is not specified, a set of well-known, standard system look-aside lists is displayed. The set of lists is not exhaustive; that is, it does not include all system look-aside lists. Also, the set does not include custom look-aside lists that were created by calls to ExInitializePagedLookasideList or ExInitializeNPagedLookasideList.

If Address is omitted (or 0) and the -all option is specified, all look-aside lists are displayed.

Controls what operation will be taken. The following possible Options are supported. The default is zero:

Displays information about the specified look-aside list or lists.

Resets the counters of the specified look-aside list.

Modifies the depth of the specified look-aside list. This option can only be used if Address is nonzero.

Specifies the new maximum depth of the specified look-aside list. This parameter is permitted only if Address is nonzero and Options is equal to 2.

Additional Information

For information about look-aside lists, see the Windows Driver Kit (WDK) documentation and Microsoft Windows Internals, by Mark Russinovich and David Solomon. (These resources may not be available in some languages and countries.)


Look-aside lists are multiprocessor-safe mechanisms for managing pools of fixed-size entries from either paged or nonpaged memory.

Look-aside lists are efficient, because the routines do not use spin locks on most platforms.

Note that if the current depth of a look-aside list exceeds the maximum depth of that list, then freeing a structure associated with that list will result in freeing it into pool memory, rather than list memory.

Here is an example of the output from this extension:

!lookaside 0xfffff88001294f80

Lookaside "" @ 0xfffff88001294f80  Tag(hex): 0x7366744e "Ntfs"
    Type           =       0011  PagedPool RaiseIfAllocationFailure
    Current Depth  =          0  Max Depth  =          4
    Size           =        496  Max Alloc  =       1984
    AllocateMisses =          8  FreeMisses =          0
    TotalAllocates =     272492  TotalFrees =     272488
    Hit Rate       =         99% Hit Rate   =        100%




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