From here: http://support.microsoft.com/kb/2267427
Memory, Committed Bytes: This is a measure of the demand for virtual
memory. It shows how many bytes have been allocated by processes and
to which the operating system has committed a RAM page frame or a page
slot in the pagefile (or both). As Committed Bytes grows above the
available RAM, paging increases, and the amount of the pagefile in use
also increases. At some point, paging activity starts to significantly
affect perceived performance.
From here: http://blogs.technet.com/b/markrussinovich/archive/2009/03/26/3211216.aspx
The kernel and device drivers use nonpaged pool to store
data that might be accessed when the system can’t handle page faults.
The kernel enters such a state when it executes interrupt service
routines (ISRs) and deferred procedure calls (DPCs), which are
functions related to hardware interrupts. Page faults are also illegal
when the kernel or a device driver acquires a spin lock, which,
because they are the only type of lock that can be used within ISRs
and DPCs, must be used to protect data structures that are accessed
from within ISRs or DPCs and either other ISRs or DPCs or code
executing on kernel threads. Failure by a driver to honor these rules
results in the most common crash code, IRQL_NOT_LESS_OR_EQUAL.
Nonpaged pool is therefore always kept present in physical memory and
nonpaged pool virtual memory is assigned physical memory. Common
system data structures stored in nonpaged pool include the kernel and
objects that represent processes and threads, synchronization objects
like mutexes, semaphores and events, references to files, which are
represented as file objects, and I/O request packets (IRPs), which
represent I/O operations.