The Bulldozer Review: AMD FX-8150 Tested
by Anand Lal Shimpi on October 12, 2011 1:27 AM ESTFinal Words
In many cases, AMD's FX-8150 is able to close the gap between the Phenom II X6 and Intel's Core i5 2500K. Given the right workload, Bulldozer is actually able to hang with Intel's fastest Sandy Bridge parts. We finally have a high-end AMD CPU with power gating as well as a very functional Turbo Core mode. Unfortunately the same complaints we've had about AMD's processors over the past few years still apply here today: in lightly threaded scenarios, Bulldozer simply does not perform. To make matters worse, in some heavily threaded applications the improvement over the previous generation Phenom II X6 simply isn't enough to justify an upgrade for existing AM3+ platform owners. AMD has released a part that is generally more competitive than its predecessor, but not consistently so. AMD also makes you choose between good single or good multithreaded performance, a tradeoff that we honestly shouldn't have to make in the era of power gating and turbo cores.
Bulldozer is an interesting architecture for sure, but I'm not sure it's quite ready for prime time. AMD clearly needed higher clocks to really make Bulldozer shine and for whatever reason it was unable to attain that. With Piledriver due out next year, boasting at least 10-15% performance gains at the core level it seems to me that AMD plans to aggressively address the shortcomings of this architecture. My only concern is whether or not a 15% improvement at the core level will be enough to close some of the gaps we've seen here today. Single threaded performance is my biggest concern, and compared to Sandy Bridge there's a good 40-50% advantage the i5 2500K enjoys over the FX-8150. My hope is that future derivatives of the FX processor (perhaps based on Piledriver) will boast much more aggressive Turbo Core frequencies, which would do wonders at eating into that advantage.
AMD also shared with us that Windows 7 isn't really all that optimized for Bulldozer. Given AMD's unique multi-core module architecture, the OS scheduler needs to know when to place threads on a single module (with shared caches) vs. on separate modules with dedicated caches. Windows 7's scheduler isn't aware of Bulldozer's architecture and as a result sort of places threads wherever it sees fit, regardless of optimal placement. Windows 8 is expected to correct this, however given the short lead time on Bulldozer reviews we weren't able to do much experimenting with Windows 8 performance on the platform. There's also the fact that Windows 8 isn't expected out until the end of next year, at which point we'll likely see an upgraded successor to Bulldozer.
So what do you do if you're buying today? If you have an existing high-end Phenom II system, particularly an X4 970 or above or an X6 of any sort, I honestly don't see much of a reason to upgrade. You're likely better off waiting for the next (and final) iteration of the AM3+ lineup if you want to stick with your current platform. If you're considering buying new, I feel like the 2500K is a better overall part. You get more predictable performance across the board regardless of application type or workload mix, and you do get features like Quick Sync. In many ways, where Bulldozer is a clear win is where AMD has always done well: heavily threaded applications. If you're predominantly running well threaded workloads, Bulldozer will typically give you performance somewhere around or above Intel's 2500K.
I was hoping for Bulldozer to address AMD's weakness rather than continue to just focus on its strengths. I suspect this architecture will do quite well in the server space, but for client computing we may have to wait a bit longer for a more competitive part from AMD. The true culprit for Bulldozer's lackluster single-threaded performance is difficult to track down. The easy answer would seem to be clock speed. We've heard of issues at Global Foundries and perhaps Bulldozer is the latest victim. If AMD's clock targets were 30% higher than Phenom II, it simply didn't make them with the FX-8150. I've heard future derivatives will focus more on increasing IPC indepedent of process technology and clock speed, but if you asked me what was the one limit to success I would say clock speed. As a secondary factor, AMD appeared to make some tradeoffs to maintain a reasonable die size at 32nm. Even then Bulldozer can hardly be considered svelte. I suspect as AMD is able to transition to smaller transistor geometries, it will be able to address some of Bulldozer's physical shortcomings.
The good news is AMD has a very aggressive roadmap ahead of itself; here's hoping it will be able to execute against it. We all need AMD to succeed. We've seen what happens without a strong AMD as a competitor. We get processors that are artificially limited and severe restrictions on overclocking, particularly at the value end of the segment. We're denied choice simply because there's no other alternative. I don't believe Bulldozer is a strong enough alternative to force Intel back into an ultra competitive mode, but we absolutely need it to be that. I have faith that AMD can pull it off, but there's still a lot of progress that needs to be made. AMD can't simply rely on its GPU architecture superiority to sell APUs; it needs to ramp on the x86 side as well—more specifically, AMD needs better single threaded performance. Bulldozer didn't deliver that, and I'm worried that Piledriver alone won't be enough. But if AMD can stick to a yearly cadence and execute well with each iteration, there's hope. It's no longer a question of whether AMD will return to the days of the Athlon 64, it simply must. Otherwise you can kiss choice goodbye.
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ThaHeretic - Saturday, October 15, 2011 - link
Here's something for a compile test: build the Linux kernel. Something people actually care about.Loki726 - Monday, October 31, 2011 - link
The linux kernel is more or less straight C with a little assembly; it is much easier on a compiler frontend and more likely to stress the backend optimizers and code generators.Chromium is much more representative of a modern C++ codebase. At least, it is more relevant to me.
nyran125 - Saturday, October 15, 2011 - link
Whats the point in having 8 cores, if its not even as fast as an intel 4 core and you get better performance overall with intel.. Heres the BIG reality, the high end 8 core is not that much cheaper than a 2600K. Liek $20-60 MAX> Youd be crazy to buy an 8 core for the same price as an intel 2600K...LIKE MAD!!!
Fiontar - Saturday, October 15, 2011 - link
Well, these numbers are pretty dismal all around. Maybe as the architecture and the process mature, this design will start to shine, but for the first generation, the results are very disappointing.As someone who is running a Phenom II X6 at a non-turbo core 4.0 Ghz, air cooled, I just don't see why I would want to upgrade. If I got lucky and got a BD overclock to 4.6 Ghz, I might get a single digit % increase in performance over my Phenom II X6, which is not worth the cost or effort.
I guess on the plus side, my Phenom II was a good upgrade investment. Unless I'm tempted to upgrade to an Intel set up in the near future, I think I can expect to get another year or two from my Phenom II before I start to see upgrade options that make sense. (I usually wait to upgrade my CPU until I can expect about a 40% increase in performance over my current system at a reasonable price).
I hope AMD is able to remain competitive with NVidia in the GPU space, because they just aren't making it in the CPU space.
BTW, if the BD can reliably be overclocked to to 4.5Ghz+, why are they only selling them at 3.3 Ghz? I'm guessing because the added power requirements then make them look bad on power consumption and performance per watt, which seems to be trumping pure performance as a goal for their CPU releases.
Fiontar - Saturday, October 15, 2011 - link
A big thumbs down to Anand for not posting any of the over-clock benchmarks. He ran them, why not include them in the review?With the BD running at an air cooled 4.5 Ghz, or a water cooled 5.0 Ghz, both a significant boost over the default clock speed, the OC benchmarks are more important to a lot of enthusiasts than the base numbers. In the article you say you ran the benchmarks on the OC part, why didn't you include them in your charts? Or at least some details in the section of the article on the Over-clock? You tell us how high you managed to over-clock the BD and under what conditions, but you gave us zero input on the payoff!
Oscarcharliezulu - Saturday, October 15, 2011 - link
...was going to upgrade my old amd3 system to a BD, just a dev box, but I think a phenom x6 or 955 will be just fine. Bit sad too.nhenk--1 - Sunday, October 16, 2011 - link
I think Anand hit the nail on the head mentioning that clock frequency is the major limitation of this chip. AMD even stated that they were targeting a 30% frequency boost. A 30% frequency increase over a 3.2 GHz Phenom II (AM3 launch frequency i think) would be 4.2 GHz, 17% faster than the 3.6 GHz 8150.If AMD really did make this chip to scale linearly to frequency increases, and you add 17% performance to any of the benchmarks, BD would roughly match the i7. This was probably the initial intention at AMD. Instead the gigantic die, and limitations of 32nm geometries shot heat and power through the roof, and that extra 17% is simply out of reach.
I am an AMD fan, but at this point we have to accept that we (consumers) are not a priority. AMD has been bleeding share in the server space where margins are high, and where this chip will probably do quite well. We bashed Barcelona at release too (I was still dumb enough to buy one), but it was a relative success in the server market.
AMD needs to secure its spot in the server space if it wants to survive long term. 5 years from now we will all be connecting to iCloud with our ARM powered Macbook Vapor thin client laptops, and a server will do all of the processing for us. I will probably shed a tear when that happens, I like building PCs. Maybe I'll start building my own dedicated servers.
The review looked fair to me, seems like Anand is trying very hard to be objective.
neotiger - Monday, October 17, 2011 - link
"server space where margins are high, and where this chip will probably do quite well."I don't see how Bulldozer could possibly do well in the server space. Did you see the numbers on power consumption? Yikes.
For servers power consumption is far more important than it is in the consumer space. And BD draws about TWICE as much power as Sandy Bridge does while performs worse.
BD is going to fail worse in the server space than it will in the consumer space.
silverblue - Monday, October 17, 2011 - link
I'm not sure that I agree.For a start, you're far more likely to see heavily threaded workloads on servers than in the consumer space. Bulldozer does far better here than with lightly threaded workloads and even the 8150 often exceeds the i7-2600K under such conditions, so the potential is there for it to be a monster in the server space. Secondly, if Interlagos noticably improves performance over Magny Cours then coupled with the fact that you only need the Interlagos CPU to pop into your G34 system means this should be an upgrade. Finally, power consumption is only really an issue with Bulldozer when you're overclocking. Sure, Zambezi is a hungrier chip, but remember that it's got a hell of a lot more cache and execution hardware under the bonnet. Under the right circumstances, it should crush Thuban, though admittedly we expected more than just "under the right circumstances".
I know very little about servers (obviously), however I am looking forward to Johan's review; it'd be good to see this thing perform to its strengths.
neotiger - Monday, October 17, 2011 - link
First, in the server space BD isn't competing with i7-2600K. You have to remember that all the current Sandy Bridge i7 waste a big chunk of silicon real estate on GPU, which is useless in servers. In 3 weeks Intel is releasing the 6 core version of SB, essentially take the transistors that have been used for GPU and turn them into 2 extra cores.Even in highly threaded workloads 8150 performs more or less the same level as i7-2600K. In 3 weeks SB will increase threaded performance by 50% (going from 4 cores to 6). Once again the performance gap between SB and BD will be huge, in both single-threaded and multi-threaded workloads.
Second, BD draws much higher power than SB even in stock frequency. This is born out by the benchmark data in the article.