a CPU question

[Flyby]

I know it's dumb, but the FORCE compels me to ask. Two CPUs to chose from. All things being equal (cores, clocks, architecture), the only difference in them is one has 8mb of L2 (or L3) cache and the other has 12mb of the same cache. From a sim-er's perspective, which is the better choice (think LOMAC/FC, Black Shark, FSX, RoF **Sow_BoB**), and why?

effya-doe-nax-ya-doe-no :lol:

Flyby out

Edited August 28, 2009 by Flyby
explosive diarrhea!

[sweinhart3]

As long as your comparing same architecture (i.e Intel chips to Intel chips or Amd chips to Amd chips) larger cache amounts will always give an extra boost in performance reguardless of application. So an Intel extreme chip running at 3Ghz with 12MB cache verse a non extreme chip running with 8MB will have a slight performance advantage. The purpose of cache memory is L1, L2, or L3 is to feed the cpu with instructions that it needs to use often. L1 cache is the fastest memory, is usually clocked at the same frequency as the CPU and its always on the CPU die and usually only in quantities like 256KB. L2 cache is a bit slower than L1 cache but in greater quantities like 1 or 2MB. L3 cache is the slowest of the 3 and because its in large quantities like 8MB or 12MB, its often packaged out side of the CPU die itself. Not all CPUs have lvl3 cache. All of these memories are however much faster for the CPU to access than main memory. To receive 1 byte of information from main memory, the CPU often has to wait around many cycles for the information to reach the CPU because it has to go thru interconnects and memory controllers etc all which have associated latencies. If a piece of information from memory is requested from the CPU it goes into cache memory first. The reason for this is so that if the CPU needs that same piece of memory often, it can pull it from the cache instead of main memory.

Thats generally how and why cache works. But you cant compare an Intel 3Ghz chip with 8MB cache and an AMD 3Ghz chip with 8MB cache and expect the same performance. Obviously this is because they are two different architectures.

[Flyby]

ah, sweinhart. I just replied toy ur comments in that other thread: http://forums.eagle.ru/showthread.php?t=44589&page=2 Good stuff you mention there. So thanks for replying here too. More good info to know. ;) I never knew which level of cache was faster, never even considered it. Didn't know exactly why it was there, either, not specifically so. So thanks again. Keep enlightening the forums like this and I'm sure your rep will grow quickly.

Flyby out