L2 Cache size ???

[Vulcan 0]

hey....

 

i saw this a few days ago :

 

"L2 Cache size

 

Windows XP can't detect the proper amount of L2 cache on your CPU. you'll want to go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\ and change the SecondLevelDataCache key to the L2 cache size of your CPU (in Kb). I've received a few questions about this one and I thought I'd clarify it. when you select to modify this file the default entry is in hexadecimal simply change the selection to decimal and THEN enter your number. Such as 256, 512. A value of 100 in Hexadecimal will result in 256Kb being shown since that is what it's decimal number is."

 

this value in my registry is 0.

should i change it ?

 

thanks !!

[Sampson 0]

This depends on the size of the L2Cache. Use this chart as a guide:

SecondLevelDataCache

for 256kB Level 2 Cache = 0

for 512kB Level 2 Cache = 200

for 1024kB Level 2 Cache = 400

[Vulcan 0]

i do have a pentium 4 1.6a with 512kb level 2 cache.

i should change the registry to 200h ?

 

question:

 

 

how come you said 256d = 0h...??

 

shouln't it be 100h ??

[Sampson 0]

The mystery of Microsoft. Apparently, 256 is baseline and starts at 0.

[Davros 0]

In XP it is set at the default of 256 (the setting of 0) regardless of your cpu. In other words, it does not detect your L2 cache, so you have to set it manually. If you have 512 you should set it to 200.

[Palos 0]

WOW...now this is what I call a ****up. Im speechless....

[clutch 1]

No, you should not have to change it as it is automatic. Very early generations of CPUs needed this adjustment, but that isn't the case now. The value of "0" simply means "automatic" and the OS will try to get the value from the HAL (explained here). Also, this setting only is only effective for systems with direct-mapped cache, and in your case setting it manually would not have any bearing on performance at all (explained here). As for the value of "0" being equal to 256, that's more of an effect of the default value scheme. If the OS can't find the cache size (with the automatic setting of "0"), then it will default to "256" as the cache size. Hence, 0=256, kinda sorta...

 

[Davros 0]

Well, that clears up that bad misconception!

[PsychoSword 0]

I heard the same thing about Windows 2000 not being able to detect it and that it's default is also 256kb. I have a Duron 700 and I believe the cache is 96kb? So what should I set mine too in Windows 2000?

[Vulcan 0]

hey clutch ,

..according to the microsoft article :

"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."

 

so why shouldn't i set it to 512,just in case ?

[clutch 1]

If you would like to, then by all means go ahead. I just wouldn't bother with it myself as it shows it only works for a form of L2 cache that hasn't existed since before the P2 line came out.