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How to Configure the Paged Address Pool and System Page Table Entry Memory Areas
Article ID: 247904 - View products that this article applies to.
This article was previously published under Q247904
NoticeThis article applies to Windows 2000. Support for Windows 2000 ends on July 13, 2010. The Windows 2000 End-of-Support Solution Center
(http://support.microsoft.com/?scid=http%3a%2f%2fsupport.microsoft.com%2fwin2000)is a starting point for planning your migration strategy from Windows 2000. For more information see the Microsoft Support Lifecycle Policy
This article describes how to adjust the size of the Paged Address Pool and System Page Table Entry (SystemPTE) memory areas in Windows 2000-based computers running the Microsoft Terminal Server service.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/322756/ )How to back up and restore the registry in Windows
Windows 2000 can directly address up to 2^32 bytes or 4 gigabytes (GB) of memory address space, regardless of how much physical Random Access Memory (RAM) is installed. By default, 2 GB of this address space is allocated to each process, and 2 GB is allocated to the kernel. While separate 2 GB regions of address space are used for each process in the computer, most of the 2 GB kernel area is global and remains the same no matter which user-mode process is currently active.
The 2 GB of kernel area contains all system data structures and information. Therefore, the 2 GB kernel address space area can impose a limit on the number of system data structures and the amount of kernel information that can be stored on a computer, regardless of how much RAM is installed.
The two types of data that share a portion of this 2 GB address area are Paged Pool allocations, and kernel stack allocations. Paged Pool allocations are memory allocations made by kernel-mode components. Kernel stack allocations are stacks created in the kernel for each thread to use for making system calls. Paged pool allocations are made in the Paged Pool area, and kernel stack allocations are made in the System Page Table Entry (PTE) area.
While these different allocations share the same area, the partition between them is fixed at startup. If the operating system runs out of space in one of those areas, the other area cannot donate space to it, and programs may begin to encounter unexpected errors. Therefore, when you encounter a Windows 2000-based computer that is experiencing unexpected errors or an inability to accept new logins, and the computer does not have some other resource limitation such as Central Processing Unit (CPU) or disk bottlenecks, it is highly likely that the Paged Pool or System PTE areas are becoming low on disk space. Because, by default, the System PTE area is sized to be as large as possible on a computer with Terminal Services enabled, the limitation will usually be due to insufficient Paged Pool address space. Fortunately on some computers, the System PTE area can be configured to be smaller, which can alleviate these symptoms and allow more users access to the computer.
To determine if your computer has run out of one or more of these resources:
151981When you believe the system has reached a limit:
(http://support.microsoft.com/kb/151981/EN-US/ )How to Set Up a Remote Debug Session Using a Null Modem Cable
*** Virtual Memory Usage ***The "********** Excessive Paged Pool Usage *****" entry in this output listing is indicative of a computer that is low on paged pool resources. This may be confirmed by noting that the PagedPool Usage entry is very close to the PagedPool Maximum entry.
Physical Memory: 1032075 ( 4128300 Kb)
Page File: \??\C:\pagefile.sys
Available Pages: 599741 ( 2398964 Kb)
ResAvail Pages: 894259 ( 3577036 Kb)
Modified Pages: 757 ( 3028 Kb)
NonPagedPool Usage: 15084 ( 60336 Kb)
NonPagedPool Max: 71586 ( 286344 Kb)
PagedPool 0 Usage: 22953 ( 91812 Kb)
PagedPool 1 Usage: 4324 ( 17296 Kb)
PagedPool 2 Usage: 4315 ( 17260 Kb)
PagedPool 3 Usage: 4360 ( 17440 Kb)
PagedPool 4 Usage: 4366 ( 17464 Kb)
********** Excessive Paged Pool Usage *****
PagedPool Usage: 40318 ( 161272 Kb)
PagedPool Maximum: 40960 ( 163840 Kb)
Shared Commit: 30133 ( 120532 Kb)
Special Pool: 0 ( 0 Kb)
Free System PTEs: 47920 ( 191680 Kb)
Shared Process: 99141 ( 396564 Kb)
PagedPool Commit: 40318 ( 161272 Kb)
Driver Commit: 770 ( 3080 Kb)
Committed pages: 822746 ( 3290984 Kb)
Commit limit: 2037826 ( 8151304 Kb)
Total Private: 545122 ( 2180488 Kb)
In order to configure the partition between System PTE space and Paged Pool space on a computer with a clean Windows 2000 installation, the computer must be out of paged pool resources, and the computer must have a significant amount of Free System PTE space remaining. The amount of Free System PTE space should be 40,000K or greater. If the computer is out of Free System PTE space, you cannot use the following method to get more users logged in to Terminal Server.
To tune the computer for the optimal balance between paged pool space and system PTE space: