low memory caches on AMD chips

[MrPink]

i have noticed, actually it is something I always saw but never asked about it. AMD cpus only have level two caches of about 4 megabytes on their newest phenom(e?) chips. these are supposed to be the new wave of high powered desktop quad cores that AMD has been promising, but what's with the low cache size of 4MB? I am only saying this is low in comparison to the intel chips whose quad cores have up to 8MB on the level 2 cache (even some 45nm ones with 12MB level two caches).

Are the larger intel numbers a sign of less efficient design, or is it insignificant like the low core clock of most AMD chips compared to Intel (though AMD clocks are climbing, the newest X2's are 3.0GHz and higher)

[tuanming]

The new wave of phantom failed to deliver the expectation for the people who been waiting for it. Bigger cache doesn't always mean more speed at least that what I believe in. Higher clock frequency, more IPC (instructions per clock/cycle), cores, and architecture. Now that is how Intel cpus (Core 2) are so fast. Oh yeah, overclocking is another key element to Intel processors .

[Cid Highwind]

Only for <5% of the market, and that's probably an over-estimation tuanming But yeah, to us it matters a friggin' lot. But indeed, bigger numbers does not equal better performance. Like with the Prescott, they needed bigger cache to cover up for the weaknesses in the chip itself. I don't know the details anymore though, but it also had to do with the pipeline and all. Pretty technical for sure.

[tuanming]

Well, most of the editorial reviews based on the phantom was pretty much what i said above and amd couldn't even deliver the 2.4Ghz or 2.6Ghz this year, tsk, tsk. What worst was that they (amd) have been dropped from the world's top 10 chips manufacturer's and they canceled/kill off the quad fx platform... No good news these days for Amd.

[ViperXtreme]

well, most amd cpu's have higher L1 cache than intel's...but still not faster hehe...

[22point8]

Something to do with the memory controller is on the CPU?

[tuanming]

Well, Amd have L3 cache (2mb i believe) but it still doesn't out perform Intel Core 2 cpus. Intel just have a superior architecture with faster IPC and high overclockability and some other improvements as well It's takes THAT much combination/efforts to make a great selling product(s). Funny how the AMD integrated memory controller on a chip doesn't really help amd much when it comes to performance. Maybe Intel will AMD how it'd be done correctly with the upcoming new 45nm code-name, Nehalem.

[guest.r]

I find the Amd L3 cache re-approach very inventive. I guess 2MB L3 + 4x512KB L2 was way faster as only 4x512KB L2 when the designers made their tests.
Dunno how fast 4x1MB L2 or 4MB of shared L2 would turn out since the same ammount of mem is discussed. Maybe they found THE solution regarding multi-core cpu cache management.

It must be considered though that phenoms are a 3 complex instruction per cycle design and therefore very fast for their frequencies.

I guess when they finish their 4+ IPC designs on 45nm that this will bring them back in the game. They should do something like that or even better.