L2 cache

[Shetland]

2MB vs 3MB vs 6MB

what is the big difference?

i.e in gaming, in photoshopping, in general computer use.

incase its needed, the rest of the system specs would include 3 gigs of ram, dedicated gfx card etc.

Edited October 12, 2008 by Shetland

[Budious]

Cache is like high-speed ram, it holds the most immediate registers of instructions and data to be processed. L1 cache runs full speed at the rate of the CPU clock speed, L2 runs half speed in most architectures. L1 must be contained in L2, and L2 must be contained in L3 (if applicable) or in RAM. The larger the cache, the more immediately available the CPU is able to switch between running processes.

This is a very simplified explanation to say the least.

[Shetland]

would you say there is a big realworld difference between four and six megs of l2 though?

[CrashG]

would you say there is a big realworld difference between four and six megs of l2 though?

No not really, I have a E6550 w/4mb cache and a E8200 w/6mb cache. Can't tell any real difference.

[P!P]

No not really, I have a E6550 w/4mb cache and a E8200 w/6mb cache. Can't tell any real difference.

Games love L2 cache. Other than that, you won't see much difference with just 2MB more.

[CrashG]

Games love L2 cache. Other than that, you won't see much difference with just 2MB more.

Still didn't notice any difference, even with the clock speed increase too. :laugh:

[MrA]

Cache is like high-speed ram, it holds the most immediate registers of instructions and data to be processed. L1 cache runs full speed at the rate of the CPU clock speed, L2 runs half speed in most architectures. L1 must be contained in L2, and L2 must be contained in L3 (if applicable) or in RAM. The larger the cache, the more immediately available the CPU is able to switch between running processes.

This is a very simplified explanation to say the least.

Not true. Some systems have exclusive caches like the AMD Athlon.

As for performance, it depends on the app. Here is a (very) detailed article describing caches. To boil it down, more cache is most beneficial when:

- you have many cores sharing a cache

- you have many programs running (i.e. you have a large working set)

- you have few programs running that use memory a lot (large working set)

So games, photoshop, and even folding would benefit from a larger cache. However, it's more complicated than that. Signal processing apps (software radio is one I've worked with) can have large data sets, but not benefit from a large cache simply because of the way memory is used.

EDIT: The full article on memory, everything you'll ever need to know is at:

http://people.redhat.com/drepper/cpumemory.pdf

[+shift. MVC]

Based on looking at benchmarks, it really only makes a significant impact in gaming performance. However, when you're comparing 6MB L2 cache to 3MB L2 cache to 4MB L2 cache there's barely any difference. But when you're comparing 1MB to 3MB or 4MB then there's probably going to be significant performance differences.

[Shetland]

i ask because it could save me a hell of alot with this dell laptop i want to buy, the way the configure it is that you jump up in clock speed aswell as cache so as to bump the price up in larger chunks. i dunno what i will do yet, we shall see. hopefully there will be a january sale and i'll get the higher end one at the price of the one under it :p