Microsoft KB Archive/815411

= Heap Algorithm Update for Atypically Large Heap Requests =

Article ID: 815411

Article Last Modified on 8/29/2007

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APPLIES TO


 * Microsoft Windows Server 2003, 64-Bit Datacenter Edition
 * Microsoft Windows Server 2003, Enterprise x64 Edition
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Tablet PC Edition
 * Microsoft Windows XP Media Center Edition 2002
 * Microsoft Windows XP Professional for Itanium-based systems
 * Microsoft Windows XP Professional for Itanium-based systems
 * Microsoft Windows Small Business Server 2003 Premium Edition
 * Microsoft Windows Small Business Server 2003 Standard Edition

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SYMPTOMS
This fix in the Windows XP Service Pack 1 (SP1) and Windows Server 2003 heap algorithm was released to better handle a particular atypical and uncommon sequence of heap requests by a private, internally developed program that is not commercially available. This program allocated and freed large chunks from the heap tens of thousands of times. The original scope and the size of the improvement for the particular program were mistakenly overstated in a prior version of this article based on an internal test application designed to reproduce the symptom, and is not relevant for any known programs or overall system performance. Typical Windows operation and common business, home, gaming and Internet programs will not be affected by this fix. It is not recommended that you use this fix except to address the specific program.



CAUSE
Windows XP SP1 and Windows Server 2003 contain a general purpose, well understood memory / heap algorithm that delivers fast performance for memory requests made from a broad spectrum of Windows programs. The performance of the algorithm in Windows has been evaluated with many industry benchmarks and by careful analysis of typical end-user operations. As with any general purpose algorithm, an atypical sequence of requests can be tailored. In this instance, the algorithm does not perform optimally. However, because such a sequence is not found in typical Windows programs or the system, you do not have to change the heap algorithm. Changing the heap algorithm does not provide for an improvement in system performance for most users and programs.

This hotfix provides a workaround in the heap algorithm to better handle a particular atypical and uncommon sequence of heap requests. The atypical request pattern was found in a custom-built program that does not bear much resemblance to the vast majority of other Windows programs in existence. The scope and the size of this hotfix is narrowly defined for this one particular program and the workaround has no benefit for the majority of programs or overall system performance.



Windows XP service pack information
To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack

Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel. Windows XP

Date        Time   Version            Size    File name --  28-Feb-2003  19:05  5.1.2600.1177     654,336  Ntdll.dll

Windows XP 64-Bit Edition Version 2002

Date        Time   Version            Size    File name --  28-Feb-2003  19:05  5.1.2600.1177   1,508,352  Ntdll.dll        IA64 28-Feb-2003 14:55  5.1.2600.1177     657,408  Wntdll.dll       X86

Windows Server 2003

Date        Time   Version            Size    File name --  03-Jun-2003  14:30  5.2.3790.49       716,800  Ntdll.dll

Windows Server 2003 64-Bit Editions and Windows XP 64-Bit Edition Version 2003

Date        Time   Version            Size    File name --  03-Jun-2003  14:24  5.2.3790.49     1,524,224  Ntdll.dll        IA64 03-Jun-2003 14:30  5.2.3790.49       711,168  Wntdll.dll       X86



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Microsoft Windows XP Service Pack 2.

Note This article was revised on 4/12/2003 to more accurately reflect the specific purpose and details of the fix. The original title of this article gave the false impression that this was a problem facing many, if not most, Windows XP users who installed SP1. In fact, the problem affects a very small number of customers who are using a privately designed program that exhibits behavior that the hotfix was created to address. (This article was previously published under the title: “Programs Run Slower After You Install Windows XP SP-1”. The contents of the hotfix itself have not changed, only the Knowledge Base documentation was revised for improved accuracy and clarity.

Keywords: kbhotfixserver kbqfe kbwinxpsp2fix kbenv kbqfe kbwinxppresp2fix kbfix kbbug kbprb KB815411

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