What is L3 Cache?

0 votes
asked Aug 31, 2010 by Craighton (16,556 points)
What is L3 Cache and what is its primary use? Like what is its use?

2 Answers

+1 vote
answered Aug 31, 2010 by kevin (35,790 points)
L3 keeps copies of requested items in case a different core makes a subsequent request. The advantage of having on-board cache is that it’s faster, more efficient and less expensive than placing separate cache on the motherboard.

More info at <http://www.wisegeek.com/what-is-l3-cache.htm>
+2 votes
answered Aug 31, 2010 by djmoore711 (2,051 points)
You could think of it as the buffer for your CPU, between the RAM and the CPU. Technically it's now in front of the North Bridge now, but nontheless, it's a <I>very</I> high-speed buffer for the CPU. You can now see how having a bigger cache on the CPU is better. Other than speed, this is usually a driving cost behind any CPU. It is extremely fast memory. The more threads you have (pipelines) they more you may need. Normal chips come with L1, L2, and L3; each one is bigger, and due to this size, is slower, also. Data flows from RAM > North Bridge > L3 > L2 > L1 > CPU.

For example, on the new Intel Core i7: L1 (32KB <I>per core</I> Instruction, 32KB <I>per core</I> Data), L2 (256KB  <I>per core</I> Instruction and Data), L3 (Up to 8MB used for all applications).

Hope that helps.
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