informal I wouldn't say that, It's an improvement over BD but still under Deneb IPC and we all know originally It should have been better than K10.
informal I wouldn't say that, It's an improvement over BD but still under Deneb IPC and we all know originally It should have been better than K10.
I never argue about ipc even before Zambezi being announced.Originally Posted by TESKATLIPOKA
When you go over the history you'll find something similar to nowaday situation. K6 have 10% higher IPC than K7, netburst is terrible, and now bulldozer is the same. Reanson why they developed a lower IPC model is because the frequency is bottlenecked by architecture. These design always not only need tweak but more important is the process node, lately CPU bottlenecked below 4Ghz and now bulldozer makes a breakthrough.
Bulldozer = K7, and it would be another K8 when everything is OK, since then don't be surprise to see a CPU that stock at 6Ghz+.
Wrong, K7 had much higher IPC than K6, K6-III was far behind P2 overall (not integer), and P3 was behind K7. And the frequency is not bottlenecked by architecture, all architectures have a hard time over 4GHz. So it's stupid to sacrifice lots of IPC and die size to squeeze a few hundred MHz more from the chip at these frequencies, every 100Mhz over 4GHz has a high price, AMD decided to pay up. I can't imagine Intels factories being capable of producing BD at competitive frequencies (5-7GHz with less power consumption). The problem is in the design, they decided to pay a high price to get some extra frequency, just the thing that killed Prescott.
No architecture with lower IPC than its predecessor has been successful. All the really successful architectures has had large gains in IPC, like Core i7, Core 2, Athlon 64, K7 and Pentium Pro.
Last edited by -Boris-; 11-18-2011 at 06:16 AM.
Completely wrong. Frequencies are bottlenecked by both the process (AKA transistor switching speed) and architecture (AKA number of sequentially placed transistors on critical path). And resulting processor frequency is a result of division of the first by the second. Bulldozer significantly shortens critical path and so it's frequency is much higher than 32nm Llano within the same power budget. Or you should expect ~4,1 Gz base clock for imaginery 6-core 45nm Bulldozer within the power budget of 1100T.
Last edited by sergiojr; 11-18-2011 at 07:29 AM.
That's flawed logic. Being 30% behind in a bench is not the same thing as being 30% slower. BD needs much more than 28% more performance to match SB.
Of course architecture matters, but what you don't take in to consideration is that frequencygains isn't linear. And over 4GHz the sacfrifices you have to do to gain each MHz isn't worth it at this point. You can't say that Bulldozer is more efficient than K10 or Llano, Bulldozer is less power efficient tha K10 on 45nm! Your comparision to Llano doesn't work since Llano has an integrated GPU, you don't know how much power the cores in Llano consumes and you don't know how the GPU affects the cores power consumption. If llano is made on a different kind of silicon to make the GPU work good enough then that could cripple energy efficieny in the cores.
It is not processor frequencies that are not linear. It is transistor frequencies, that are. But as I said before processor frequency ~ transistor frequency/ critical path. So if there is a hypothetical 4Ghz barrier for K10 on 45nm, then this barrier will be around 5Ghz for Bulldozer on the same 45 nm techprocess (I assume that Bulldozer's critical path is around 1,25 times shorter based on Llano and Bulldozer 4-core frequencies and power consumption in CPU-dependent tasks).
It is because 32nm techprocess is currently worse the 45nm (est. 5-10%). Of course it saves costs, but performance wise it's just worse. Probably they will match with Q1 2012 Bulldozer update.You can't say that Bulldozer is more efficient than K10 or Llano, Bulldozer is less power efficient tha K10 on 45nm!
There is something like 2,6Ghz 100W non-GPU LlanoYour comparision to Llano doesn't work since Llano has an integrated GPU, you don't know how much power the cores in Llano consumes and you don't know how the GPU affects the cores power consumption. If llano is made on a different kind of silicon to make the GPU work good enough then that could cripple energy efficieny in the cores.
http://products.amd.com/en-us/Deskto...False&f12=True
Not a fair comparison of course, but at least it is much more then you have to backup you claim.
Last edited by sergiojr; 11-18-2011 at 09:29 AM.
Again you forget leakage, if it wasn’t any leakage in the processor then it would behave that way you say. But if you get rapidly increasing leakage at a transistor level at 4GHz then you get that no matter the length of your critical path. And since 130nm leakage problems have been a growing issue. Before leakage became a problem you could see 50-100% frequency gain each node on the same architecture. After 2GHz that has been much less so, and above 3GHz it has been really slow. In the old days you could get twice the frequency by adding stages and shortening each stage, today you simply can’t do that for the same reason a new process don’t get twice the frequency anymore. Intel discovered this the hard way with P4, their short pipelined high IPC products could almost match their deep pipelined Prescott with low IPC, for an end result of much higher performance. That’s why IPC has been so important the last 5+ years. A deep pipeline which traditionally allows much higher frequencies has lost its advantage when both experience the same increasing leakage at a transistor level.
You can’t say for sure that’s the process. Intel have an incredibly good process with their 32nm, but SB-E with roughly the same size as Bulldozer consumes roughly the same power. Intels very good process just isn’t that good when you make a 2 billion trannie chip! So, that intels process gets just as bad when they try to make a gargantuan chip themselves is an indication that the size is too big to manufacture at lower power or higher frequencies.
And that doesn’t meanwhen it’s still made to be a full Llano with the same tradeoffs in silicon and transistor types. So you have nothing that points at 32nm being that bad. You can’t use Llano as an example since you don’t know which processes it’s made on! A GPU with hundreds of shaders might consume incredible amounts of power if it’s made on a processes tuned for high frequency like a CPU. And a CPU clocked at normal frequencies despite being made on a process made for low frequencies like a GPU will also consume more power and be a very bad overclocker. Intel don’t have this problem since their GPUs is tailored from the ground up to be on the same process as a CPU, an indication of this is the record breaking frequencies it’s GPU runs at and its small size, the drawback is that it doesn’t scale to well when you make it large like a traditional GPU.
No,I meant 5-10% better IPC over what we have with this Bulldozer.Not what we have with Deneb.
Posting Permissions
Reply With Quote
Bookmarks