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The "HeapDecommitFreeBlockThreshold" registry key
Article ID: 315407 - View products that this article applies to.
This article was previously published under Q315407
This article describes the HeapDecommitFreeBlockThreshold registry key.
When memory is freed at a given address, the heap manager checks how many contiguous bytes are free around that address. After that check is complete, the heap manager can do one of two things:
Note On computers that have one gigabyte or more of RAM, apply the following setting for maximum performance:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager HeapDeCommitFreeBlockThreshold = REG_DWORD 0x00040000On computers that have less than one gigabyte of RAM, do not use the HeapDecommitFreeBlockThreshold registry key unless intense memory fragmentation is occurring.
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
By default, the heap manager does not necessarily combine all free blocks or make new allocations; therefore, blocks may be de-committed and become useless holes in the virtual address space. The HeapDecommitFreeBlockThreshold registry key provides better control of how the memory is handled as it is freed. To add this key, you need to edit the registry.
To add the HeapDecommitFreeBlockThreshold registry key:
Article ID: 315407 - Last Review: October 25, 2007 - Revision: 5.5