What is a L1/L2 cache???

Hello friends,

i want to know what exactly does L1/L2 cache means in processor,graphics card?? Though i have searched in detail but still not satisfied with the information....so need help from my community/forum members & friends....:)

This might be most dumb question as far as the forum standards are concerned...(i know people might also say that it not as no question is dumb or silly) but this statement is directed only to me guys....

Thanks Richard that was useful & got some more knowledge about the same...its just i can't understand more when its used for graphics card....any info on the same...

I'm no expert on this stuff but I don't think it applies to graphics card processors. I don't remember ever seeing it listed in the specs for a card, just the amount of onboard video RAM.

1) The idea behind cache memory is that RAM is much slower than the CPU. Now, if the CPU had to wait for RAM for every new byte of instructions or data, it would be ridiculously slow. Of course, ideally, your ENTIRE RAM could be on the CPU chip itself, running at the same speed as the CPU's core, but that would be very expensive.

To work around this, manufacturers add a small amount of fast RAM as "cache". Although the first time the CPU needs data, it has to wait for the RAM, when that data finally arrives, a copy is saved in the cache. The next time the CPU next needs data from a nearby address, there is a high chance that the data is in the cache, which means no delay in reading it into the CPU.

The bigger the cache, the more it can hold but the more expensive it is. Normally CPUs have a small "L1" cache which runs at full CPU core speed and a slower "L2" cache or both.

2) L1 and L2 are normally not used in the context of GPU though i believe newer GPUs like Fermi have added that feature.

HPCwire: NVIDIA Takes GPU Computing to the Next Level

Bill2 said:

L1 and L2 are normally not used in the context of GPU though i believe newer GPUs like Fermi have added that feature.

That's right & that's what i was referring to the nVidia Fermi & other latest GPUs do use cache term...i read an artcile in a computer magazine when Fermi was being launched & they showed how it work & also kept using L1/L2 cache in the entire article so i was little confused too...