The Bulldozer Review: AMD FX-8150 Tested
by Anand Lal Shimpi on October 12, 2011 1:27 AM ESTThe Pursuit of Clock Speed
Thus far I have pointed out that a number of resources in Bulldozer have gone down in number compared to their abundance in AMD's Phenom II architecture. Many of these tradeoffs were made in order to keep die size in check while adding new features (e.g. wider front end, larger queues/data structures, new instruction support). Everywhere from the Bulldozer front-end through the execution clusters, AMD's opportunity to increase performance depends on both efficiency and clock speed. Bulldozer has to make better use of its resources than Phenom II as well as run at higher frequencies to outperform its predecessor. As a result, a major target for Bulldozer was to be able to scale to higher clock speeds.
AMD's architects called this pursuit a low gate count per pipeline stage design. By reducing the number of gates per pipeline stage, you reduce the time spent in each stage and can increase the overall frequency of the processor. If this sounds familiar, it's because Intel used similar logic in the creation of the Pentium 4.
Where Bulldozer is different is AMD insists the design didn't aggressively pursue frequency like the P4, but rather aggressively pursued gate count reduction per stage. According to AMD, the former results in power problems while the latter is more manageable.
AMD's target for Bulldozer was a 30% higher frequency than the previous generation architecture. Unfortunately that's a fairly vague statement and I couldn't get AMD to commit to anything more pronounced, but if we look at the top-end Phenom II X6 at 3.3GHz a 30% increase in frequency would put Bulldozer at 4.3GHz.
Unfortunately 4.3GHz isn't what the top-end AMD FX CPU ships at. The best we'll get at launch is 3.6GHz, a meager 9% increase over the outgoing architecture. Turbo Core does get AMD close to those initial frequency targets, however the turbo frequencies are only typically seen for very short periods of time.
As you may remember from the Pentium 4 days, a significantly deeper pipeline can bring with it significant penalties. We have two prior examples of architectures that increased pipeline length over their predecessors: Willamette and Prescott.
Willamette doubled the pipeline length of the P6 and it was due to make up for it by the corresponding increase in clock frequency. If you do less per clock cycle, you need to throw more clock cycles at the problem to have a neutral impact on performance. Although Willamette ran at higher clock speeds than the outgoing P6 architecture, the increase in frequency was gated by process technology. It wasn't until Northwood arrived that Intel could hit the clock speeds required to truly put distance between its newest and older architectures.
Prescott lengthened the pipeline once more, this time quite significantly. Much to our surprise however, thanks to a lot of clever work on the architecture side Intel was able to keep average instructions executed per clock constant while increasing the length of the pipe. This enabled Prescott to hit higher frequencies and deliver more performance at the same time, without starting at an inherent disadvantage. Where Prescott did fall short however was in the power consumption department. Running at extremely high frequencies required very high voltages and as a result, power consumption skyrocketed.
AMD's goal with Bulldozer was to have IPC remain constant compared to its predecessor, while increasing frequency, similar to Prescott. If IPC can remain constant, any frequency increases will translate into performance advantages. AMD attempted to do this through a wider front end, larger data structures within the chip and a wider execution path through each core. In many senses it succeeded, however single threaded performance still took a hit compared to Phenom II:
At the same clock speed, Phenom II is almost 7% faster per core than Bulldozer according to our Cinebench results. This takes into account all of the aforementioned IPC improvements. Despite AMD's efforts, IPC went down.
A slight reduction in IPC however is easily made up for by an increase in operating frequency. Unfortunately, it doesn't appear that AMD was able to hit the clock targets it needed for Bulldozer this time around.
We've recently reported on Global Foundries' issues with 32nm yields. I can't help but wonder if the same type of issues that are impacting Llano today are also holding Bulldozer back.
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Elric42 - Thursday, December 1, 2011 - link
I wanted to say one thing i dont have one but a friend of mine does and he showed me somthing my i5 cant do he was playing a game called crissis if thats how u spell it and running a video editting program at he same time well i cant do that with my i5 if i did the game would start to lag crissis takes alot out of your cpu bad programing even video cards have trouble with the game but bd seems to muti task better then what my i5 can do just wondering if its more for peeps who do alot of stuff at one time.ZyferXY - Monday, January 2, 2012 - link
Thanks for pointing that out because not so long ago i saw a video on amd's web site where they were showing of a amd Llano notebook vs a intel sandy bridge core i7 notebook they started the same benchmark on both notebooks and the intel was quite fast but as they open more and more programs at the same time the intel starts to drop in performance where the amd is running stable. So my suggestion would be to run all benchmark on the bulldozer and i7 2600k again but this time open about 10 or 20 other programs a the same time then u will truly see the bulldozer shine. I am not a amd fanboy my current build a intel Pentium G860 and i am very dissapointed in myself i shouldve gone with the amd q640 it was around the same price when i bought it. My next build will be a Amd FX4100. HAmakaira - Thursday, December 8, 2011 - link
Well I very excitedly bought a 8150 based system for number crunching as the performance/$ looked very good. I could buy a "quiet" system for Aus $ 1130 with SSD and only 8Gb RAM.I had previously purchased a Intel i7 2600K, but could never get it to overclock and run 64 bit Java app (Napoleon Spike from DUG) 24/7, it fell over after 6 hrs or 12 or 23 or 47, it always fell over despite water cooling.
Now the bulk of my work is done by Xeons in the rack, with a couple of dual 5680's systems doing the heavy lifting (2 x 6 core + hyperthreading looks like 24 CPU's to OS). These are good stable systems with 96Gb RAM, but high overall system cost.
I wanted a few cheap and moveable fast CPU's. Boy did the Bulldozer fail to deliver
More is Better measure in Bytes inversion throughput/minute
BD 8150 115-123k in 8/8 threads i.e. flat out
i7 2600 237-268k in 8/8 threads i.e. flat out
Xeon dual 5680 333-356k in 12/24 threads i.e.half loaded
i7-870 166k in 8/8 threads i.e flat out
Xeon Dual E5520 190k 12/16 threads
Xeon Dual 5430 132k 8/8 threads
The Bulldozer is the slowest and the newest....very poor performance. Eclipsed by Intel at similiar price point. I might as well replace the MB and CPU and go with i73960 or 3930...
wepexpert117 - Thursday, December 8, 2011 - link
I dunno if anyone noticed, but if u study the architectures carefully, then what AMD calls as a 'module' is comparable to a 'core' of Intels. Intels Hyperthreading allows two logical thread executions per core. But AMD's TruCore theory, only allows one thread per core. The Intel i5-2500K has 4 physical cores and 8 logical threads. Compared to that the most powerful of the AMD, the FX-8170, contains 4 modules which can execute 8 threads, with 2 cores per module, each core executing 1 thread. On the other hand the i7-2600K contains 6 physical cores and 12 logical threads. Hence by no chance, can the FX-8150, can match the capability of the 2600K, as the latter as 2 more cores to add to the power. As for the results of the benchmarking, it also agrees with the fact that the FX-8150 is comparable albeit a little less powerful than the i5-2500K, because of the architecture difference between Intels core and AMD's Bulldozer.If AMD ever brings out (according to them) a 12 core FX processor (Prob. FX-12XXX), then it would be really interesting to see how that matches with the i7-2600K. Altough the shared L2 cache architecture, is what may be detrimental to the performance of these processors.Jondenmark - Saturday, December 24, 2011 - link
Something is wrong. If I look at a die shot of Llano then the core is about 1½ times the size of the 1 MB L2 cache. If I look at a Bulldozer module, it is about 1½ times the 2 MB L2 cache. To me this indicates, that a Buldozer module is about 100% larger than a phenom II core which is far from the 12% more core size, which AMD has previously indicated was the cost of adding another core to form a module. The 12% was expected to allow AMD to add nearly double the core count on a given process node to convince the server market and give plenty of die space for the GPU on the Llano APU. Where am I wrong and what is right?8 core cpu - Friday, January 6, 2012 - link
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Raven0628 - Saturday, January 14, 2012 - link
I beleive amd realy missed it shoot badly, but it is still the right social choice caus what will happen if intel get x86 monopol and they are still resonably priced and whene you have to live with it in every day life will you realy notice the diferance in perfomance. Unless you realy to go for all the top of the line in every part of your system you will got for the top of intel i7.But i'v never did and alway ended up with reliable good perfomance amd sys for less than 800$ counting with the power supply i had to replace. this year. my point unless you want a death machine go for amd and you will feel better with your self ;).
PS. sry for the terible english.
Ernst0 - Sunday, February 5, 2012 - link
Hey guys.There is no doubt that whatever critiques have been posted are valid but I skimmed a few pages and saw no "Consumer" comments.
I have purchased an 8150 with a AMD3+ motherboard and will be putting the unit together.
In my days since the Z80 and 48k this represents the nicest cpu ever for me.
That it was affordable and that I will have 8 cores to task with my hobby programming such as trying to factor RSA-numbers or the ilk the AMD 8=core is a dream system for the price.
I picked up case, mother board power supply, 1.5 TB drive DVD, 1 gb video, 16 gb ram, 28 inch monitor, wall mount for monitor so I can have two 28's with one the long way for source code and perhaps something else.. Anyway $1200 is the cost.
Now this is my first bare-bones experience too so all in all it is exciting to get such a dream machine and I am happy to step forward and support AMD
I don't know what awaits when the memory arrives and I boot up but it feels like Starship already and I have vowed to learn OpenMP under GCC to advance into multi-core programming.
So perhaps there will be issues. perhaps this is not all that nor is it wat will come but from where I am at I am still on the AMD home team and my money is flowing in the economy.
I went from trs 80 to Amiga then to twin AMD single core chips on one Motherboard, Moved to the early quad cores dreaming of dual quad cores when a system with 8 cores of that day would have cost $4900 and now picked up a system that as a boy in 1973 I would have considered Alien-ufo technology for about what I paid for dual single core chips just a few years ago.
So BullDozer can't be all that bad. The price is good! I will see how she runs. I often peg cores at 100% for days when searching for RSA factors.. Looks like I get more bang for the same bucks this time and I am all for that.
Thank you AMD for such a wonderful cpu. I plan to make use and thanks to the motherboard I can watch out for heat issues much easier than ever,
Not to mention it looks like the sound system is way advanced over the last computer as well.
So from a consumer / hobby programmer point of view this is very cool indeed.
Ernst
mumbles - Sunday, February 12, 2012 - link
Thank you for being the first to actually contribute some real world response to this architecture. So many trolls on this thread that are intel fanboys.Also, if your using xen with this thing, I would be interested in seeing some feedback on how multiple guests(like more than 4) act when trying to fight for floating point processor time. Be interesting also to see if 4 floating point threads and 4 integer threads can all run at the same time with no waiting. That might be asking too much for now tho.