Windows Vista Forums
Vista Forums Home Join Vista Forums Windows 7 Forum Vista Tutorials Tags
Welcome to Windows Vista Forums. Our forum is dedicated to helping you find solutions with any problems, errors or issues you are experiencing with Windows Vista. The Vista forum also covers news and updates and has an extensive Windows Vista tutorial section that covers a wide range of tips and tricks.

Go Back   Vista Forums > Vista Forums > Tutorials

Vista - CPU L2 Cache Memory setting in Vista

Comment
 

CPU L2 Cache Memory setting in Vista

How to Set Vista for the CPU L2 Cache Memory Size
Published by Brink
07-05-2007

How to Set Vista for the CPU L2 Cache Memory Size
Information
  The SecondLevelDataCache records the size of the processor cache, also known as the secondary or L2 cache. If the value of this entry is 0, Vista will attempt to retrieve the L2 cache size from the Hardware Abstraction Layer (HAL) for the platform. If Vista fails for some reason to retrieve the L2 cache size from HAL, then it uses a default CPU L2 cache size of only 256 KB. If the default value of the SecondLevelDataCache value is not 0, Vista will use the value (amount of memory) you set instead of 0 (for 256 KB) as the L2 cache size of. This value is designed as a secondary source of cache size information for Vista when the HAL cannot detect the L2 cache from the CPU.
NOTE
  This sets the SecondLevelDataCache inside the registry.

From Microsoft KB183063:


Quote  Quote: Originally Posted by Microsoft KB183063
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 CPU L2 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 CPU has a 2 MB L2 cache) would probably have about a 0.4 percent performance penalty.
WARNING
  Only set the value to what your processor actually has for the L2 cache size. Do not use a larger size than it actually has.
RELATED LINKS:

STEP ONE:
Find Out the L2 Cache Size Reported by HAL
NOTE
  This will show you how to see what the L2 cache size is for your CPU as it is reported to Vista by HAL. This value will be used in STEP TWO below to set the SecondLevelDataCache value for this as a backup in case HAL rarely could not detect the L2 cache from the CPU.
1. Generate a System Health Report.

2. Click on the Hardware Configuration arrow on the far right to expand it. (See screenshot below step 3)

3. Click on the Devices arrow on the far right to expand it. (See screenshot below)
arrows.jpg
4. Under Devices, scroll down to Motherboard Classes. (See screenshot below step 5)
A) Click on the + sign to expand
root\cimv2:SELECT * FROM Win32_Processor.

B) Click on the + sign to expand
Win32_Processor.DeviceID="CPU0".
5. In that list, you will see L2CacheSize and the value beside it for it's size to use it in step 6 in STEP TWO below.
NOTE: For this example you will see 6144 to be used for my CPU's 2x6144 (12MB) L2 size. Now, here's a kicker. The newer Yorkfield Core 2 Quads CPUs use the entire cache for both cores unlike the older CPUs that do not share. So a 2x6144 (12mb) L2 cache would use 12288 (2x6144) instead despite what is reported in Vista for HAL.
system_health_report.jpg

STEP TWO:
Set the L2 Cache Size
NOTE
  This will set the SecondLevelDataCache value in the registry, from the value gotten in STEP ONE, as a backup in case HAL rarely could not detect the L2 cache from the CPU and prevent having only a default L2 cache size of 256 KB used as L2 cache size instead by Vista.
1. Open the Start Menu.

2. In the white line (Start Search) area, type regedit and press Enter.

3. Click on Continue in the UAC prompt.

4. In regedit, go to: (See screenshot below)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management

5. In the right pane, right click SecondLevelDataCache and click on Modify.
before_reg.jpg
6. Dot Decimal, and type in the value in bold (see table below) for your CPU L2 size from STEP ONE above. (See screenshot below table)
NOTE: I have a CPU with a 2x6144 (12MB) L2 cache size, so I would use 6144 (Dec) or 1800 (Hex) since it is 2x. See STEP ONE above for how to get the L2 size for your CPU. Now, here's a kicker. The newer Yorkfield Core 2 Quads CPUs use the entire cache for both cores unlike the older CPUs that do not share. So a 2x6144 (12mb) L2 cache would use 122488 (Decimal) or 3000 (hex) instead despite what is reported in Vista for HAL.
Decimal Value Hexadecimal Value
256 KB100 (hex)
512 KB200 (hex)
1024 KB (1MB)400 (hex)
2048 KB (2MB)800 (hex)
3072 KB (3MB) c00 (hex)
4096 KB (4MB)1000 (hex)
6144 KB (6MB)1800 (hex)
8192 KB (8MB)2000 (hex)
12288 KB (12MB)3000 (hex)
16384 KB (16MB)4000 (hex)
Name:  Modify.jpg
Views: 28566
Size:  13.6 KB
7. Click on OK to apply.

8. Your registry will look like this below for a 2x6144 (12MB) L2 cache memory size.
NOTE: See STEP ONE above to find out your CPU L2 cache size.
after_reg.jpg
9. Close regedit.

10. Restart the computer to apply the change.
That's it,
Shawn

Published by
Brink's Avatar
Administrator

Join Date: Apr 2007
Location: Texas, USA
Posts: 25,919
Rep Power: 150
Brink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond reputeBrink has a reputation beyond repute

Tutorial Tools

Applies to
All Vista Versions
64 Bit & 32 Bit

Old 07-21-2007  
Grimace


 
 

Re: CPU L2 Cache Memory setting in Vista

Shawn I just thought id inform that for reson unknown to me the 4mb cache setting isnt 1600.

Its actually 1000. I am unsure as to why cause all the rest are correct.

Cheers
Anthony

My System SpecsSystem Spec
Old 07-21-2007  
Brink


Vista x64 Ultimate SP2, Windows 7 Ultimate x64
 
 

Re: CPU L2 Cache Memory setting in Vista

Anthony,

Thank you.
Nice catch. It has been updated.

Shawn
My System SpecsSystem Spec
Old 11-19-2007  
maineearle


Vista Home Basic
 
 

Re: CPU L2 Cache Memory setting in Vista

How do you determine L2 cache size to make these mods
My System SpecsSystem Spec
Old 11-19-2007  
Brink


Vista x64 Ultimate SP2, Windows 7 Ultimate x64
 
 

Re: CPU L2 Cache Memory setting in Vista

Hi Maineearle,

You need to look up your CPU's specs to see that it says. Go to the manufacturer's website to do so.(EX: Intel or AMD) You can find the model number to look it up with by right clicking Computer (in Start menu) and click Properties. You can also find the model number in System Information.

Shawn
My System SpecsSystem Spec
Old 11-19-2007  
z3r010


Windows 7 Ultimate x64
 
 

Re: CPU L2 Cache Memory setting in Vista

Wouldn't something like cpuid give you the info
My System SpecsSystem Spec
Old 11-19-2007  
Brink


Vista x64 Ultimate SP2, Windows 7 Ultimate x64
 
 

Re: CPU L2 Cache Memory setting in Vista

Thank you,

Why, yes it will. It's a standalone EXE program. No need to install, just run the EXE. You can find the information under the CPU tab under Cache Level 2.

http://www.cpuid.com/cpuz.php

Shawn
My System SpecsSystem Spec
Old 11-19-2007  
Violent Ken


Vista Ultimate x64
 
 

Re: CPU L2 Cache Memory setting in Vista

q6600 has 2x 4096 L2, so i put in 1000?
it's set to 0 currently
My System SpecsSystem Spec
Old 11-19-2007  
Asky


Windows Vista X64
 
 

Re: CPU L2 Cache Memory setting in Vista

^i dunno if we can put 2000(since brink hasnt mentioned it) so better put 1000 to be safe.
My System SpecsSystem Spec
Old 11-19-2007  
Brink


Vista x64 Ultimate SP2, Windows 7 Ultimate x64
 
 

Re: CPU L2 Cache Memory setting in Vista

Quote  Quote: Originally Posted by Violent Ken View Post
q6600 has 2x 4096 L2, so i put in 1000?
it's set to 0 currently
Hi Violent Ken,

This means that you have 8 Mb shared cache between the 4 cores. You should use 2000 as the value. I updated the tutorial for this.

You can read more on your Intel Core 2 Quad Q6600 processor here:

http://www.intel.com/products/processor/core2quad/index.htm


Quote:
Quad-Core Processor:
Provides four complete execution cores in a single processor with 8 MB of L2 cache and a 1066 MHz Front Side Bus. Four dedicated, physical threads help operating systems and applications deliver additional performance, so end users can experience better multi-tasking and multi-threaded performance across many types of applications and work loads.
Quote:
Intel Advanced Smart Cache:
Shared Level 2 cache across each pair of cores that can be dynamically allocated to each processor core, within the pair can access data from fast L2 cache, significantly reducing latency to frequently used data and improving performance.
Shawn
My System SpecsSystem Spec
Comment

Tutorial Tools


Similar Threads
Tutorial Category
Solved 16MB Cache and 32MB Cache?? General Discussion
Erasing contact memory cache Vista mail
Setting virtual memory progrmmatically Vista General
Setting Virtual Memory Vista installation & setup
"This device does not allow its write cache setting to be modified" Vista General


Vista Forums is an independent web site and has not been authorized,
sponsored, or otherwise approved by Microsoft Corporation.
"Windows Vista", the Start Orb, and related materials are trademarks of Microsoft Corp.
© Designer Media Ltd
Tutorial powered by GARS 2.1.8m ©2005-2006

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46