The Bulldozer Review: AMD FX-8150 Tested
by Anand Lal Shimpi on October 12, 2011 1:27 AM ESTThe Impact of Bulldozer's Pipeline
With a new branch prediction architecture and an unknown, but presumably significantly deeper pipline, I was eager to find out just how much of a burden AMD's quest for frequency had placed on Bulldozer. To do so I turned to the trusty N-Queens solver, now baked into the AIDA64 benchmark suite.
The N-Queens problem is simple. On an N x N chessboard, how do you place N queens so they cannot attack one another? Solving the problem is incredibly branch intensive, and as a result it serves as a great measure of the impact of a deeper pipeline.
The AIDA64 implementation of the N-Queens algorithm is heavily threaded, but I wanted to first get a look at single-core performance so I disabled all but a single integer/fp core on Bulldozer, as well as the competing processors. I also looked at constant frequency as well as turbo enabled speeds:
Unfortunately things don't look good. Even with turbo enabled, the 3.6GHz Bulldozer part needs another 25% higher frequency to equal a 3.6GHz Phenom II X4. Even a 3.3GHz Phenom II X6 does better here. Without being fully aware of the optimizations at work in AIDA64 I wouldn't put too much focus on Sandy Bridge's performance here, but Intel is widely known for focusing on branch prediction performance.
If we let the N-Queens benchmark scale to all available threads, the performance issues are easily masked by throwing more threads at the problem:
However it is quite clear that for single or lightly threaded operations that are branch heavy, Bulldozer will be in for a fight.
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JumpingJack - Sunday, November 6, 2011 - link
This is a good point.mianmian - Wednesday, October 12, 2011 - link
How disappointed I am. I can't believe what AMD will claim later on.Marburg U - Wednesday, October 12, 2011 - link
Cannot see a reason to wait for Piledriver. Am3+ won't survive that chip, and +15%, even in single thread, won't be enough (for Sandy, I'm not even talking about Ivy).If BD had not been so bad i would have hoped in a price drop of the Thuban, and would have gone for it. But now, i fear price spikes of the old Phenom II X6 as it approaches it's EOL.
Ethaniel - Wednesday, October 12, 2011 - link
... using a chainsaw. Newegg sells a 2500k for USD 220. I'm thinking something like 170-180 for the FX-8150. I was expecting a lot from the FX line. And I think that was my mistake, probably. Too bad.Leyawiin - Wednesday, October 12, 2011 - link
I guess we can take comfort in that some things never change - naming AMD processors are always behind the curve (since before Intel's C2 Duo). Guess I'll hang onto my X4 955 @ 3.6 Ghz for a while longer. It'll be the last AMD processor I'll bother with (and I'm tired of being faithful and waiting on them).richard77aus - Wednesday, October 12, 2011 - link
""At the same clock speed, Phenom II is almost 7% faster per core than Bulldozer according to our Cinebench results.""I am far from being an expert in CPUs but isn't the main advantage intel has had since core2- sandybridge the per core performance? not closk speed and not multi core.
I've seen some benchmarks showing real world usage of the SB i3 dual core where it out performs a faster clocked quad core phenom 2.
richard77aus - Wednesday, October 12, 2011 - link
Meaning AMD giving first priority to clockspeed and core count was the wrong thing to aim for even if they had achieved a 4ghz+ stock 8 core speed processor, but to actually go backwards compared to such an old arch. is a disaster. (my first post here, is there a way to edit posts?)Kristian Vättö - Wednesday, October 12, 2011 - link
The thing is that Phenom II, which is AMD's arch, is FASTER clock for clock than their new Bulldozer arch. Intel is far ahead of both CPUs, but it's a bit laughable that AMD's older CPUs actually outperform their new ones.Saxie81 - Wednesday, October 12, 2011 - link
Hey Anand, did you happen to get the power consumption numbers when you hit 4.7ghz?This is... disappointing. I knew the Single thread benchmarks were going to be bad, but you need to be running something thats needing the 8 cores, if not its of no use. Kinda like using a Magny Cours to run Crysis.
Anand Lal Shimpi - Wednesday, October 12, 2011 - link
I'm going to be doing some more overclocking tomorrow, but I broke 300W at 4.7GHz :-/