Modifying the Level 2 Cache for Windows XP Acceleration

Among the many XP optimization techniques, the more popular one is that Windows XP requires the user to manually open the CPU's L2 cache so that the CPU can maximize its efficiency. . This argument is widely spread, and the "Windows Optimizer", one of the most used Windows system optimization software, has this view. In its optimization settings bar, there is an option to optimize the CPU's L2 cache.

Let's first take a look at how this so-called optimization technique tells us.

[Windows XP system, the CPU secondary cache is not turned on by default. In order to improve system performance, we can open it by modifying the registry or by using software such as "Windows Optimizer".

Run the registry editor, expand the HKEY_LOCAL_MacHINE\\System\\CurrentControlSet\\Control\\Session Manager\\Memory Management branch, double-click "SecondLevelDataCace" in the right window, and then fill in the current computer directly in the pop-up window. The secondary cache capacity of the CPU used is sufficient.

The Celeron processor's L2 cache is 128KB, and its value should be set to 80 (hexadecimal, the same below). PII, PIII, P4 are all 512KB L2 cache, should be set to 200; PIIIE (EB), P4 Willamette only 256KB L2 cache, should be set to 100; AMD Duron only 64KB L2 cache, should be set to 40; K6- 3 has 256KB L2 cache; Athlon has 512KB L2 cache; Athlon XP has 256KB L2 cache; Athlon XP (Barton core) has 512KB L2 cache.

Using Windows Optimizer can also correctly set the CPU's L2 cache: Start Windows Optimizer, select "System Performance Optimization", in "File System Optimization", the top is about the CPU L2 cache settings. item. Once you drag the slider to the appropriate location, save your settings and restart your computer. 】

Is this really the case?

We found the following in Microsoft's knowledge base: The value of the SecondLevelDataCache key in "HKLM\\SYSTEM\\CurrentControlSet\\Control\\Session Manager\\Memory Management" is only available in the Windows XP system from the hardware abstraction layer ( Hardware Abstraction Layer ) The data of the SecondLevelDataCache key is read when the CPU L2 cache (L2) fails to read. And the meaning of the SecondLevelDataCache key value = 0 is 256KB for the second level cache.

In a Knowledge Base article, we also found the words "Do not change the SecondLevelDataCache entry". In the article, it is pointed out that some third-party data claim that modifying the value of the SecondLevelDataCache key can improve the system performance. . The value of the L2 cache is detected by the operating system and is completely unaffected by the SecondLevelDataCache value.

From the Microsoft Knowledge Base article we can see that the so-called Windows XP system requires users to manually open the secondary cache is wrong. The Windows XP system reads the secondary cache value of the CPU based on the hardware abstraction layer. The value of SecondLevelDataCache is read only when the read fails, and the default value of 0 of SecondLevelDataCache represents the meaning of the second level cache is 256KB instead of closing. Therefore, the secondary cache of the CPU is turned on at any time, and the user does not need to modify it.