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I have seen on some blogs the differences regarding Committed Bytes and Pool Nonpaged Bytes. I thought both were reserved memories for NT systems that cannot be written to a pagefile.sys. So what is the diffenrence?

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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

Nonpaged Pool 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.

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