Detailed Explanation of SecondLevelDataCache (183063)
The information in this article applies to:
- Microsoft Windows NT Server 4.0
- Microsoft Windows NT Workstation 4.0
- Microsoft Windows NT Server, Enterprise Edition 4.0
This article was previously published under Q183063 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:
256986 Description of the Microsoft Windows Registry
SUMMARY
This article discusses the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
\Memory Management\SecondLevelDataCache
REG_DWORD
Range: Kilobytes 0, 1 -cache size
Default: 0 (256K)MORE INFORMATIONWARNING: 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.
SecondLevelDataCache records the size of the processor cache, also known as
the secondary or L2 cache. If the value of this entry is 0, the system
attempts to retrieve the L2 cache size from the Hardware Abstraction Layer
(HAL) for the platform. If it fails, it uses a default L2 cache size of 256
KB. If the value of this entry is not 0, it uses this value as the L2 cache
size. This entry is designed as a secondary source of cache size
information for computers on which the HAL cannot detect the L2 cache.
This is not related to the hardware; it is only useful for computers with
direct-mapped L2 caches. Pentium II and later processors do not have direct-
mapped L2 caches. SecondLevelDataCache can increase performance by
approximately 2 percent in certain cases for older computers with ample
memory (more than 64 MB) by scattering physical pages better in the address
space so there are not so many L2 cache collisions. Setting
SecondLevelDataCache to 256 KB rather than 2 MB (when the computer has a 2
MB L2 cache) would probably have about a 0.4 percent performance penalty.
| Modification Type: | Major | Last Reviewed: | 6/11/2002 |
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| Keywords: | kbinfo KB183063 |
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