Vista - CPU L2 Cache Memory setting in Vista

**Brink** · 07-05-2007

How to Set Vista for the CPU L2 Cache Memory Size

...

Click here to read the entire tutorial

**abovesecret** · 07-26-2008

Thanks for the reply Shawn. I tried that method and it works like it should. Great site by the way. Im a total noob when it comes to vista and for me this site is a blessing.

**Brink** · 07-26-2008

Your welcome AboveSecret.

Shawn

flazza · 08-09-2008

Sorry if this is a stupid question

what do you put if it is dual cpu?

I have a dell precision 490 with 2x3ghz dual cores with each processor having 4mb cache (2048 KB per core)

**Brink** · 08-10-2008

Hi Flazza, and welcome to Vista Forums.

For the Dual-Core Intel® Xeon® 5160 3.0GHz, 1333 FSB, 4MB L2 Cache, 80 watts processor you would use 4MB (4096) since it's L2 memory is shared.

http://www.intel.com/business/enterp...Xeon_Brief.pdf

Quote:

Dual-Core Intel® Xeon® Processor 5100 Series

4M shared cache fully accessible by each core

lowering memory latency and increasing performance

Hope this helps,
Shawn

**WildEagle** · 08-15-2008

I've been testing this tweak, and it seems to work so far. I have a Core 2 Duo E6600 with 4MB of cache, which means each core has access to 2MB of cache each.

**Brink** · 08-15-2008

Hi WildEagle,

Actually, looking up your CPUs specs, it shares the 4MB L2 cache with both cores. You can set it for the full 4MB.

This PDF document from Intel shows you the specifications for all Core 2 Duo processors.

http://download.intel.com/products/p...prod_brief.pdf

**WildEagle** · 08-15-2008

That's what I did was set it for 4MB's of cache. The cache being shared between the 2 cores simply means that each core has access to 2MB of cache each.

**ltwally** · 08-15-2008

Quote: Originally Posted by WildEagle

That's what I did was set it for 4MB's of cache. The cache being shared between the 2 cores simply means that each core has access to 2MB of cache each.

Incorrect. On Core2Duo's, the cache is shared wholey by both cores. Therefore, each core sees an entire 4meg of cache - NOT 2meg of cache.

**ltwally** · 08-15-2008

It's worth re-quoting Microsoft on this registry value.

Detailed Explanation of SecondLevelDataCache

Quote:

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.

If you do some research on your processor, it is not direct-mapped. You likely have an 8-way or 16-way set-associative.

According to a little time with google, it appears that neither Intel or AMD has produced a mainstream processor with a direct-mapped L2 cache for several processor generations.

This really is an old legacy key, and can be safely left at 0. Altering it should not harm your computer - but neither will you gain anything from it.

For more information, check out the wikipedia entry.

**WildEagle** · 08-15-2008

Quote: Originally Posted by ltwally

Incorrect. On Core2Duo's, the cache is shared wholey by both cores. Therefore, each core sees an entire 4meg of cache - NOT 2meg of cache.

You obviously know nothing. 4MBs of cache just because it is shared doesn't mean each core sees 4MB's of cache, it means each core has access to 2MB only not the full 4MB's. If each had access to the full 4MB, when multitasking a game and something else that also used that cache there would be problems out the rear.

Take a look at videocards like the 3870X2 which I own, it comes with 1GB of shared videomemory, but each chip only has access to 512MB of video memory at one time.

This is how dual core cpu's and videocards such as the 3870X2 operate, there is no way, that if they operated any other way, they would get anything done.

07-05-2007
Brink Vista x64 Ultimate SP2, Windows 7 Ultimate x64 25,980 posts	CPU L2 Cache Memory setting in Vista How to Set Vista for the CPU L2 Cache Memory Size ... Click here to read the entire tutorial
My System Specs

07-26-2008
abovesecret Vista Ultimate 32bit/64bit 5 posts	Re: CPU L2 Cache Memory setting in Vista Thanks for the reply Shawn. I tried that method and it works like it should. Great site by the way. Im a total noob when it comes to vista and for me this site is a blessing.
My System Specs

07-26-2008
Brink Vista x64 Ultimate SP2, Windows 7 Ultimate x64 25,980 posts	Re: CPU L2 Cache Memory setting in Vista Your welcome AboveSecret. Shawn
My System Specs

08-09-2008
flazza vista 64bit 1 posts	Re: CPU L2 Cache Memory setting in Vista Sorry if this is a stupid question what do you put if it is dual cpu? I have a dell precision 490 with 2x3ghz dual cores with each processor having 4mb cache (2048 KB per core)
My System Specs

08-10-2008
Brink Vista x64 Ultimate SP2, Windows 7 Ultimate x64 25,980 posts	Re: CPU L2 Cache Memory setting in Vista Hi Flazza, and welcome to Vista Forums. For the Dual-Core Intel® Xeon® 5160 3.0GHz, 1333 FSB, 4MB L2 Cache, 80 watts processor you would use 4MB (4096) since it's L2 memory is shared. http://www.intel.com/business/enterp...Xeon_Brief.pdf Quote: Dual-Core Intel® Xeon® Processor 5100 Series 4M shared cache fully accessible by each core lowering memory latency and increasing performance Hope this helps, Shawn
My System Specs

08-15-2008
WildEagle Vista X64 Ultimate 332 posts	Re: CPU L2 Cache Memory setting in Vista I've been testing this tweak, and it seems to work so far. I have a Core 2 Duo E6600 with 4MB of cache, which means each core has access to 2MB of cache each.
My System Specs

08-15-2008
ltwally vista64 323 posts	Re: CPU L2 Cache Memory setting in Vista Quote: Originally Posted by WildEagle That's what I did was set it for 4MB's of cache. The cache being shared between the 2 cores simply means that each core has access to 2MB of cache each. Incorrect. On Core2Duo's, the cache is shared wholey by both cores. Therefore, each core sees an entire 4meg of cache - NOT 2meg of cache.
My System Specs

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