!lookaside

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]

Parameters

Address
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.

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

0
Displays information about the specified look-aside list or lists.

1
Resets the counters of the specified look-aside list.

2
Modifies the depth of the specified look-aside list. This option can only be used if Address is nonzero.

Depth
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 Using Lookaside Lists and Microsoft Windows Internals, by Mark Russinovich and David Solomon.

Remarks

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%

Requirements