AMD's Next-Generation Mobile Architecture Revealed: Griffin
by Anand Lal Shimpi on May 18, 2007 12:10 AM EST- Posted in
- CPUs
New Memory Controller
Although the underlying architecture of Griffin is K8 based, the memory controller takes a lot of cues from Barcelona/Phenom. There's a new DRAM prefetcher, similar but not identical to what will be in Phenom, but many of the efficiency improvements in the new desktop core will make their way to Griffin as well. Taken from our Barcelona architecture article:
"One strength of Intel's FB-DIMM architecture used in Xeon servers is that you can execute read and write requests to the AMB simultaneously. With standard DDR2 memory, you can do one or the other, and there's a penalty for switching between the two types of operations. If you have a fairly random mixture of reads and writes you can waste a lot of time switching between the two rather than performing all of your reads sequentially then switching over to writes. The K8's memory controller made some allowances for preferring reads over writes since they take less time, but in Barcelona the memory controller is far more intelligent.
Now, instead of executing writes as soon as they show up, writes are stored in a buffer and once the buffer reaches a preset threshold the controller bursts the writes sequentially. What this avoids is the costly read/write switch penalty, helping improve bandwidth efficiency and reduce latency."
AMD did not make it clear whether Griffin also featured two independent 64-bit DDR2 memory controllers or a single 128-bit one. And, of course, as the memory controller is a part of the North Bridge it operates at a separate, lower voltage than the rest of the CPU cores.
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Goty - Friday, May 18, 2007 - link
I agree with your points here, but it might have come down to an issue of time and manpower. Intel probably has teams of engineers sitting around twiddling their thumbs just waiting for something to do while AMD probably has everyone working around the clock. It's probably more a result of resources than anything.TA152H - Friday, May 18, 2007 - link
Goty,I think you're right, but a product like that could make a big difference too. It would be so different than anything out there, and have such advantages for the market it is designed for, I think it is something they should have looked at.
I guess what's so disappointing for me is they mentioned that they were going to try a completely new design for it, and then they just did another iteration of the K8 and took a branch from there. I don't think they can seriously differentiate themselves from the Core 2 line, and I think they have to. Intel is so much better in manufacturing, if AMD retains design parity, or something close, I don't know how they are going to be successful. I think Fusion is a good idea, but I don't think it's enough and I don't think it would be hard for Intel to duplicate, because as you say, they have the resources.
Besides, they have the K6, they'd have to increase the memory interface, improve the decoders, and tweak little things here and there, but it's a great processor. Remember how disappointed everyone was when the K7 couldn't beat it clock normalized for integer and it was beating the Katmais that were 50 MHz faster? This with the putrid VIA MVP3 chipset that had horrible memory performance. It was a really good design.
I am also wondering why they still have such strong x87 in the Athlons. Why even bother these days, particularly with the mobile part. Put in a tiny non-pipelined version for compatibility, and save the space for something more useful. x87 isn't even supported in x86-64 mode, so it's clearly a dead technology.
LoneWolf15 - Friday, May 18, 2007 - link
Maybe it did for Joe Sixpack, but it ticks me off. Centrino tells me nothing about what kind of processor is in a system, it just tells me that the system has a wireless card (of some sort, Intel branded but who-knows-which-model). Centrino could mean Pentium-M (Banias or Dothan), Celeron-M, or Core Solo. Centrino Duo at least tells me a system is dual-core, but not whether it's Core Duo or Core 2 Duo (or possibly "Pentium Dual Core", that relabeled Core Duo Intel is putting out in limited quantities). You call this simple? I sure don't.
I can't stand this marketing trend. There is very little way to "at-a--glance", know exactly what you are getting in a given laptop. It's just one more buzzword to know, when just saying the laptop has WiFi (which 95% do at this point) and an Intel xxx processor running at such-an-such a speed would be useful. And it looks like it gets review sites like Anandtech sucked into buzzword bingo in the process.
IntelUser2000 - Friday, May 18, 2007 - link
Actually, Celeron M based laptops can't be certified as Centrino. Here is the chart from Intel: http://www.intel.com/products/centrino/compare.htm">http://www.intel.com/products/centrino/compare.htm
And you can further differentiate the single core Centrinos from the dual cores. Dual core versions are Centrino Duo, and single core ones are Centrino. It looks like even the logo can be different for Core Solo compared to Pentium M.
acejj26 - Friday, May 18, 2007 - link
power consumption is linear with respect to frequency and quadratic with respect to voltage, not exponentialelpresidente2075 - Friday, May 18, 2007 - link
You do know that they are one in the same in this instance, right?Goty - Friday, May 18, 2007 - link
x^2 is quadratic, a^x is exponential (a being some constant).Big difference.
JarredWalton - Friday, May 18, 2007 - link
a^x is indeed exponential... and yet, x could be something like... 2! :)Seer - Friday, May 18, 2007 - link
The OP is right and you're completely wrong. I came on here to post the very same message.The definition of x in this case is that it is a variable. If both x and a were constants....you'd just have a single number. There would be no relationship. Go back to Algebra I if you truly don't understand this.
goku - Friday, May 18, 2007 - link
Seeing innovations like this where they're doing more with less just really makes me happy. It's nice to see that they're addressing power concerns and working towards having a powerful computer that also can be power conservative.While the hardware industry is getting more efficent, unfortunately the software industry is following the trend of the P4. Software is getting more and more inefficient and bloated while hardware is getting more efficient. It'd be nice if this trend would reverse and would start seeing better software written again..