PSS ID Number: 183063
Article Last Modified on 6/11/2002
--------------------------------------------------------------------------------
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 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.
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.
Keywords: kbinfo KB183063
Technology: kbWinNT400search kbWinNTS400 kbWinNTS400search kbWinNTsearch kbWinNTSEnt400 kbWinNTSEntSearch kbWinNTSsearch kbWinNTW400 kbWinNTW400search kbWinNTWsearch
