DOCUMENT:Q264450 11-JUN-2002 [winnt] TITLE :Reduced Working Set Size After Installing Windows NT SP6a PRODUCT :Microsoft Windows NT PROD/VER::4.0,4.0 SP6,4.0 SP6a OPER/SYS: KEYWORDS:kbenv kbtool kbWinNT400PreSP7Fix ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Server versions 4.0 SP6, 4.0 SP6a - Microsoft Windows NT Workstation versions 4.0, 4.0 SP6a - Microsoft Windows NT Server, Enterprise Edition versions 4.0, 4.0 SP6a ------------------------------------------------------------------------------- IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base: Q256986 Description of the Microsoft Windows Registry SYMPTOMS ======== The upper limit of a program's minimum working set can be significantly less on a Windows NT 4.0 Service Pack 6a-based computer than what it may be when you are running Windows NT 4.0 Service Pack 5 or earlier. CAUSE ===== Windows NT 4.0 Service Pack 6 addressed an issue where a user-mode program could request more physical memory than what is actually installed on the local computer. This could prevent the non-paged pool from expanding, and this can cause the system processes to run out of memory. RESOLUTION ========== A supported fix is now available from Microsoft, but it is only intended to correct the problem described in this article and should be applied only to systems experiencing this specific problem. To resolve this problem, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web: http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS NOTE: In special cases, charges that are normally incurred for support calls may be canceled, if a Microsoft Support Professional determines that a specific update will resolve your problem. Normal support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The English version of this fix should have the following file attributes or later: Date Time Size File name Platform --------------------------------------------------------------- 11/03/2000 05:31p 956,672 Ntkrnlmp.exe Intel 11/03/2000 05:30p 936,384 Ntoskrnl.exe Intel 11/03/2000 05:27p 1,409,216 Ntkrnlmp.exe Alpha 11/03/2000 05:27p 1,385,216 Ntoskrnl.exe Alpha STATUS ====== Microsoft has confirmed this to be a problem in Windows NT 4.0 SP6a. MORE INFORMATION ================ WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk. The memory manager in Windows NT 4.0 Service Pack 6 allows for non-paged pool memory to grow to its maximum size before allowing a program to increase its minimum working set size. For additional information about calculating non page pool memory, click the article number below to view the article in the Microsoft Knowledge Base: Q126402 PagedPoolSize and NonPagedPoolSize Values in Windows NT By reducing the maximum size of the non-paged pool, programs will be able to receive a larger working set size. The non-paged pool can be reduced by configuring the following new NonPagedPoolMaximumPercent registry entry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management Value Name: NonPagedPoolMaximumPercent Data Type: REG_DWORD Radix: Decimal Data: 0 or 5 - 80 0 = Keeps the old behavior (default) 5 - 80 = The percentage of RAM that is allowed to be non-paged pool. It is important to understand that excessively reducing the size of the non-paged pool may prevent Windows NT from functioning correctly. If the non-paged pool becomes exhausted, Windows NT generates Stop error messages. The Stop errors that are most likely to occur if the non-paged pool becomes exhausted include Stop 0x4D NO_PAGES_AVAILABLE, Stop 0x41 MUST_SUCCEED_POOL_EMPTY or other Stop error messages. If the NonPagedPoolMaximumPercent registry value is to be modified from the default value of 0, you should determine the current non-paged pool usage. You can do so by monitoring the following memory counter with Performance Monitor over a period of time. Examine the counter memory / non-paged pool, and find the maximum size it grows to. Use this as the minimum size the non-paged pool should be set to. However it would be strongly recommended to allocate more non-paged pool memory to allow for system usage changes. The problem with a reduced working set size is very unique, and unless a program requests an increase of its minimum working set size very significantly this problem will not be noticed. Additional query words: ====================================================================== Keywords : kbenv kbtool kbWinNT400PreSP7Fix Technology : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400 kbWinNTS400sp6 kbWinNTS400search kbWinNTSEnt400SP6a kbWinNTW400SP6a Version : :4.0,4.0 SP6,4.0 SP6a Hardware : ALPHA x86 Issue type : kbbug Solution Type : kbfix ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.