Does anyone know about it? I have been looking at the latest processors and they seem to now have Level 3 Cache. Has there always been L3 or is this a new development and if so how much better is it than the normal Level 2? For example the high-end AMD-64 processors now have 2Mb of Level 3 Cache.
i always thought AMD-64 had 1MB or 512k of L3 Cache, or am i getting mixed up with L2?
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3rd June 2004
For the longest time processors had an L2 cache. Wether it was 128K, 256K, 512K, 1M, or whatever. Now, since the P4 EE, I keep seeing new CPUs with L3. WTF is L3? One thing comes to mind, applications must be written in order to actually take advantage of it. Additionally, the same CPUs with 2MB of L3 only have 512K of L2. WTF? I think it's something that will be useful in the months and years to come, but right now, just like Hyper-Threading, it has no real use. I opted for a 3.4 Prescott over an EE simply because of that screwy L3 cache. For me, there's no reason to believe that it's even useful at this point.
dont processors still have L1, i think ive seen it somewhere, and its been like 64k+64k or somethin wierd like that
But what is different about it? What would be the advantages of it if a program was written specific for it?
jus now, ive just been reading about cache, and it was saying how L1 cache is a small amount of memory stored close to the processor for quick and easy access, this was described as the owner of a printing factory, having his own printer, so he can get things quicker because its closer. L2 cache is the same, but 'slightly further away' and L3 cache is aparently only really used in processors for servers, like Intel Xeon.
23rd January 2000
RevenBut what is different about it? What would be the advantages of it if a program was written specific for it?
The point of cache is to keep the processor pipeline fed with data. CPU cores are typically the fastest part in the computer. As a result cache is used to pre-read or store frequently used instructions and data for quick access. Cache acts as a high speed buffer memory to more quickly provide the CPU with data. * L1 cache - Then the level 1 cache comes next. It is logically the closest high speed memory to the CPU core / registers. It usually runs at the full speed (meaning the same as the CPU core clockspeed). L1 often comes in size of 8kB, 16kB, 32kB, 64kB or 128kB. But, it is very high speed even though the amount is relatively small. * L2 cache - The next level of cache is L2, or level 2. Nowadays L2 is larger than L1 and it often comes in 256kB, 512kB and 1,024MB amounts. L2 often runs at 1/4, 1/2 or full speed in relation to the CPU core clockspeed. * L3 cache - Level 3 cache is something of a luxury item. Often only high end workstations and servers need L3 cache. Currently for consumers only the Pentium 4 Extreme Edition even features L3 cache. L3 has been both "on-die", meaning part of the CPU or "external" meaning mounted near the CPU on the motherboard. It comes in many sizes and speeds.
Well thats cleared things up. Thanks, Glasius.
We should make a stickied thread answering all these questions. Cuts down on endless question posts like yours truly's.