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Discussion on Article:
AMD Discloses Peculiarities of Next-Generation Jaguar Micro-Architecture.

Started by: keysplayer | Date 09/05/12 12:33:51 AM
Comments: 38 | Last Comment:  01/16/14 04:09:30 PM

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0 5 [Posted by: keysplayer  | Date: 09/05/12 12:33:51 AM]
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Jaguar will not be found in any 40nm parts.
4 0 [Posted by: quasi_accurate  | Date: 09/05/12 12:56:22 AM]

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0 5 [Posted by: eleman  | Date: 09/05/12 12:57:55 AM]
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By your logic the ultimate processor would have 1 stage long pipeline (ie no pipelining), but of course they don't. Its so much more complicated than your simple explanation. Longer pipelines reduces the amount of gates required to implement each stage (as its smaller) which reduces the propagation delay of each step which increases maximum frequency. This is independent of IPC.

The only area a longer pipeline reduces performance is in branch misprediction, as the pipeline needs to stall as it gets flushed. However, in this case and in many cases, you can get a sizeable increase in max frequency with only a minor increase in branch misprediction penalty. It says in the article that they are getting 10% higher frequency from one stage longer pipeline, so branch misprediction has gone from 13 to 14 cycles, or a 7.7% bigger penalty. Given a branch prediction rates are ~85-90% even in the Pentium days, that 7.7% increase only occurs on 10-15% of branches (which make up ~25-33% of average code).

Long story short, 10% higher frequency, smaller than 10% penalty = net gain in performance. Its about finding the optimal point between reducing stage propagation delays (the returns get smaller the more stages you add) and the increase in branch mis-prediction (which increases linearly with pipeline length). Prescott didn't work for many reasons, not just pipeline length (which has 31 stages long, far longer than Jaguar anyway). Just saying longer pipeline = no improvement without even a basic analysis of the architecture is just incorrect.
8 2 [Posted by: genie  | Date: 09/05/12 05:37:42 AM]
Hmm... Your explanation makes sense. Thank you.
1 0 [Posted by: eleman  | Date: 09/06/12 12:27:46 AM]
All good man, I think Intel's 'megahertz at all costs' strategy during the P4 days jaded most people regarding changing architecture to support higher freq's. But like everything, the reality is always more complicated than at first glance.
0 0 [Posted by: genie  | Date: 09/06/12 11:44:16 PM]
AMD's K8 had longer pipeline than AMD K7, yet it featured _much_better IPC.
5 0 [Posted by: Anton  | Date: 09/05/12 09:35:16 AM]

Where is a "revolution" Bulldozer module design?
Where is shared FP and other resources?
Dirk, Rory is betraying your legacy which you had been bearing so many years.
1 3 [Posted by: Azazel  | Date: 09/05/12 05:49:21 AM]
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Jaguar is an evolution of the Bobcat core, which itself was a completely different design from Bulldozer and was aimed at low-power applications.
4 1 [Posted by: quasi_accurate  | Date: 09/05/12 08:45:43 AM]
Do low-power applications need powerful FP and AVX?
Would has it not been better to use sharing for FP and AVX? Would it?
Shared Fetch and Decode would have been of some use to lower power consumption in low performance cpus. Wouldn't it?
1 2 [Posted by: Azazel  | Date: 09/05/12 10:25:53 AM]

Most improvements in tech/life are evolutionary, not revolutionary. Pipeline length by itself does not determine a CPU's overall performance and is only one important factor. Jaguar is for 28nm process not 40nm. It's reported that GloFo will produce these chips as TSMC still lacks sufficient 28nm capacity.
6 2 [Posted by: beenthere  | Date: 09/05/12 06:22:12 AM]

Whilst AMD are pretty much a niche CPU company compared to the glory days of Opteron these days, their APU's are great in the space they were designed for

ppl saying AMD is finished/die would have a very rude awakening should this ever happen because then we all would be paying a lot more for those precious intel CPU's
3 1 [Posted by: alpha0ne  | Date: 09/07/12 12:36:26 AM]

Not the most exciting product but at least there is progress. One can only imagine the performance increase once they rework the L2 cache. In Bobcat the L2 cache isn't unified nor does it work at the same clocks as the rest of the cores but instead runs at half the core clocks. The gains in Jaguar very easily suggest that the L2 hasn't changed in that regard. Pity that had the L2 cache been designed like it should have it would have easily compeated with higher end products.
0 0 [Posted by: nforce4max  | Date: 01/15/13 12:30:50 PM]

This Chip has won AMD the Playstation 4 and Xbox 720 contracts..

Both consoles will have AMD Jaguar Micro-Architecture CPU's and Graphics core next GPU's... looks like they pulled off one hell of a CPU

Ohh and the product they will be selling is a custome "8" core Jaguar CPU~
0 0 [Posted by: vid_ghost  | Date: 01/24/13 04:06:19 PM]

Sony and Microsoft both made a mistake on choice of hardware! What they should of used is:

Sony should of went with Nvidia Project Denver 20nm (ARMv8 + Maxwell GPU)The PS4 would of been 2x faster then AMD Jaguar crap! Right now Nvidia has the fastest GPU for PC on Earth! GeForce GTX TITAN.

Microsoft should of used Intel 14nm Broadwell (HD Graphics 5000) Eighth generation GPU! Also would have been 2x faster then what AMD has to offer MS Xbox!

AMD has nothing to compare with 14nm Broadwell (Intel 5th gen CPU+GPU.
0 0 [Posted by: ToxicTaZ  | Date: 02/21/13 02:38:51 PM]
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There is one small problem with your theory.THERE IS NO 20NM YET.
0 0 [Posted by: saneblane  | Date: 02/27/13 01:26:19 PM]
Derp is all I got from that. Dude for how many years has AMD and NVidia been trading blows in GPU's? and since when does Intel know how to make a gpu? Yes intel processors are faster but graphics suck balls dude always have. Check out some benchies with piledriver in multi thread compete with ivy bridge. Yes it uses more power but still competes. Before you go ohh intel is the best amd sucks think about where amd is competing in. Think about the support amd cpu/gpus are gonna get after this. think about the competition, the price drops etc. Think about if both consoles are using 8 core x86/x64 cpus think about finally having developers learning about and implementing true multithread in games. Think about the fact that they are running X86/X64 architecture, really think about it (don't just ohh amd is sh*t so it doesn't matter). Think about how easy it will be to port games over to PC. No more skyrims and cods and gta4s and sh*t like that. Think about the fact that this chip won (apparently) both contracts (ps4 def but only rumors on 720) and its in an APU. Gotta be a half decent chip. Stop being a troll and realise this is a great step for intel/NVidia users aswell as will help unify instructions on all platforms. All gaming done on one hardware set. Thankyou AMD you have done a great job for the gaming industry. I hope this works out well for you!
0 0 [Posted by: Corey  | Date: 03/03/13 08:17:55 AM]
Sometimes it is interesting to read all the comments regarding this CPU/GPU thing, whos bested who and soo on, depite my lazyness on reading. I myself was a fan of AMD but now accepted both developers as part of my dayly business needs. Sure some might say AMD craps or likewise but I guess all this might give an idea of understanding on how global market and demand works and to improvise current trend and model so there is choice and direction on where to look at.. All parties benefiting from eachothers... furthermore they all share the same piece of cake. And definately have better ideas on how to get their business running for years to come.
0 0 [Posted by: Norman78  | Date: 01/16/14 04:09:30 PM]


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