PDA

View Full Version : What's the difference between L1 and L2 cache


Capt. Picard
12-03-05, 05:36 AM
What's the difference between L1 and L2 cache?

I see P4 3 GHz has L1 28K and 2MB
And the AMD 3200 has L1 128K and 512K cache.

Capt. Picard
12-03-05, 05:51 AM
3200+ 2.0GHz 1MB 754-pin
3200+ 2.0GHz 512KB 939-pin
I also see on the AMD website that one 3200 model has 1MB cache but what does the difference in pins do?

Greg
12-03-05, 06:01 AM
What's the difference between L1 and L2 cache?
I see P4 3 GHz has L1 28K and 2MB
And the AMD 3200 has L1 128K and 512K cache.
L1 is Level 1 cache, a tiny amount of very high speed memory almost instantly accessible to the CPU, L2 is level 2 cache, a much larger amount of memory, now days built into the CPU as well, but not quite as fast, though still much faster than directly accessing the real memory. CPUs typically have between 1 and 3 levels of cache memory between the CPU and the real memory. The effect is to speed memory access, and the effect is cricitcal to performance, but drops off after a certain amount. If you disable the caches, you can expect a decrease in performance by 30-90%. In general, the larger the cache the better. You will find that with AMD chips, the only difference between higher speed models is larger cache or a few hundred Mhz. You cannot compare CPUs by cache size or Ghz ratings (particularly between brands), you must compare by real world benchmarks. The design of the chip and associated chipsets is far more important than these figures alone.

Greg
12-03-05, 06:08 AM
3200+ 2.0GHz 1MB 754-pin
3200+ 2.0GHz 512KB 939-pin
I also see on the AMD website that one 3200 model has 1MB cache but what does the difference in pins do?
You should probably google for this info as there are tons of articles and posts on this kind of thing. Anyway... As years go by, the CPUs are redesigned with different pin layouts. Different models (Eg. desktop, server, mobile) also have different pin layouts due to design requirements. You cannot mix pin counts or CPU types with motherboards that are not compatible. The 754 pin is older than the 939 pin, the 939 has some new features like 'dual channel' memory controller and usually supports PCI-E which is designed for new devices like fast video cards. The 939 will be gradually replaced next year by another design. So, when buying a new system you need to find matching CPU, Motherboard and RAM. There will be a range of prices and models that are compatible, often the exact brand is not as important as the model or chipset. Before you purchase a new motherboard, I'd recommend visiting a forum like this http://forums.pcper.com/ to see what issues other people are having with the board you plan to buy.

newls1
12-03-05, 01:21 PM
L1 is Level 1 cache, a tiny amount of very high speed memory almost instantly accessible to the CPU, L2 is level 2 cache, a much larger amount of memory, now days built into the CPU as well, but not quite as fast, though still much faster than directly accessing the real memory. CPUs typically have between 1 and 3 levels of cache memory between the CPU and the real memory. The effect is to speed memory access, and the effect is cricitcal to performance, but drops off after a certain amount. If you disable the caches, you can expect a decrease in performance by 30-90%. In general, the larger the cache the better. You will find that with AMD chips, the only difference between higher speed models is larger cache or a few hundred Mhz. You cannot compare CPUs by cache size or Ghz ratings (particularly between brands), you must compare by real world benchmarks. The design of the chip and associated chipsets is far more important than these figures alone.
Exactly. You cant compare an FX57 that uses 2.8GHz, to a 2.8GHz P4. Just a LITTLE difference:eek:

superklye
12-03-05, 01:40 PM
The difference has nothing to do with the cache. Cache is cache. It has to do with the way AMD and Intel make use of each frequency cycle and the companies are radically different.

AMD is much more efficient per clock cycle, hence the lower speeds that trounce the higher clocked P4s.

And anyway...doesn't L1 run at the same speed the CPU core is running at?

seeker010
12-03-05, 03:04 PM
The difference has nothing to do with the cache. Cache is cache. It has to do with the way AMD and Intel make use of each frequency cycle and the companies are radically different.

AMD is much more efficient per clock cycle, hence the lower speeds that trounce the higher clocked P4s.

And anyway...doesn't L1 run at the same speed the CPU core is running at?
but so does L2, now at least.

superklye
12-03-05, 03:13 PM
but so does L2, now at least.
Really? I wasn't aware of that, but if it's true, that's badass.

I can't wait for chips to have 4GB of cache, negating the need for RAM all together. :D

Sazar
12-03-05, 04:29 PM
Really? I wasn't aware of that, but if it's true, that's badass.

I can't wait for chips to have 4GB of cache, negating the need for RAM all together. :D

And costing in excess of $50k :cool:

superklye
12-03-05, 06:07 PM
And costing in excess of $50k :cool:
Details, details.

TierMann
12-03-05, 06:54 PM
And costing in excess of $50k :cool:
We'll just have to use JakUp's.