The Bulldozer Aftermath: Delving Even Deeper
by Johan De Gelas on May 30, 2012 1:15 AM ESTThe Current Situation
It's not hard to explain why an 8-thread processor with slightly lower single-threaded performance does not do well in many desktop applications. If you compare for example the hex-core Core i7-3960X with a quad-core i7-3820, four games did not benefit from the extra two cores: Civilization V, Crysis, Dirt 3 and Metro 2033. In Starcraft 2, World of Warcraft, and Dawn of War 2, the 50% higher core count was good for a 10% performance boost at best. In other words, the situation has improved, but most games don't scale well beyond four cores. There are also other factors at play, though, as it's already known that StarCraft II doesn't use more than two cores; instead, it's likely the 15MB (vs. 10MB in i7-3820) L3 cache that helps improve performance.
The situation in the server space is a lot harder to explain. The Opteron 6100 was able to keep up—more or less—with the Xeon 5600 performancewise. However, the Xeon 5600 was equipped with much better power management and the Xeon won the performance/watt race in most applications, with the exception of HPC applications.
The Opteron 6200 added a bit of performance but sips much less power at low and medium load, so it was capable of offering a better performance per Watt ratio than its older brother. However, since the Xeon E5 came out, the situation became pretty dramatic for the Opteron. One telling example is the fact that only one VMmark 2.0 result on the Opteron 6200 exists, but it has been withdrawn. Even if the reported 12.77 score is close to truth, we need four AMD Opteron 6726 (2.3GHz) to beat the best dual Xeon E5 (2690 at 2.9GHz) by 15%.
We have shown already quite a few benchmarks in two Opteron 6276 articles and one Xeon E5 review. We summarized the relevant numbers of both articles in the table below. The benchmarks below are real world and very relevant to the professional in our opinion.
| Software: Importance in the market |
Opteron 6276 vs. Opteron 6174 |
Xeon E5-2660 vs. Opteron 6276 |
Virtualization: 20-50% |
||
| ESXi + Linux (vApusMark FOS) |
+1% |
+40% |
OLAP Databases: 10-15% |
|
|
| MS SQL Server 2008 R2 (OLAP throughput) |
-9% |
+34% |
HPC: 5-7% |
|
|
| LS-Dyna (Neon-Refined) |
+21% |
+26% |
Rendering software: 2-3% |
|
|
| Cinebench |
+2% |
+37% |
ERP |
|
|
| SAP |
+18% |
+13% |
Now consider that all these applications are highly-threaded and scale well. Despite the 33% higher integer core count, the Opteron 6276 is not able to outperform the older Magny-Cours in the OLAP, virtualization and rendering benchmarks. However, the architecture is showing its promise by offering about 20% better performance in SAP and HPC applications.
What makes the Bulldozer cores fail in the OLAP benchmark and succeed in SAP? We now have some interesting profiling details on SAP as well as our OLAP benchmark, so we can delve deeper.
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Taft12 - Wednesday, May 30, 2012 - link
Johan, this is the best article I've read on Anandtech in quite some time, even better than Jarred, Ryan and Anand have come up with lately.The level of analysis goes far, far beyond just what the benchmarks show.
Bravo!
JohanAnandtech - Thursday, May 31, 2012 - link
Great! Good to read there are still people that like these kinds of analysis!:-)
ct760ster - Wednesday, May 30, 2012 - link
Would be interesting if they could test the aforementioned benchmark in an OS with a customizable kernel like GNU-Linux since code optimization is not possible in most of the proprietary format benchmark.alpha754293 - Wednesday, May 30, 2012 - link
What about the lacklustre FPU performance?The very fact that the FP has to be shared between two integer cores and as far as I know, it cannot run two FP threads at the same time, so for a lot of HPC/computationally heavy workloads - Bulldozer takes a HUGE performance hit. (almost regardless of anything/everything else; although yes, it counts, but remembering that CPUs are glorified calculators, when you take out one of the lanes of the highway and two-lane traffic is now squeezed down to one lane, it's bound to get slower.)
The_Countess - Wednesday, May 30, 2012 - link
except the FP CAN run 2 threads at the same time.only for the as yet pretty much unused 256bit instructions does it need the whole FP unit per clock.
in fact the FP can run 2 threads of 128bit, or 4 even of 64bit.
and a single CPU can use 2x128bit or both can use 1x128.
intel and AMD previously had only 1x128bit capability per core.
so there is no regression in FP performance per core. its just much more flexible.
Zoomer - Wednesday, May 30, 2012 - link
FPU throughput is much more irrelevant nowadays, as many FP intensive HPC computations have already been ported to GPUs. Yes, there may be instances where there might be FP heavy and branchy, not easily parallelization or otherwise unsuitable, but such beasts are few and far between. I can't think of any, to be honest.Iger - Wednesday, May 30, 2012 - link
Thanks a lot, that was a very interesting read!Rael - Wednesday, May 30, 2012 - link
AMD should fire all its marketing department, because these guys accustomed to lie at every announcement they make. The performance gains are multiplied by five or ten, and the per-core advancement, which is close to zero, is presented as 'significant'.I don't believe these announcements anymore.
jabber - Wednesday, May 30, 2012 - link
What the whole of the AMD Marketing team?Thats Tim the caretaker and Trisha on the front desk isnt it?
I thought AMD's marketing budget was around $42.
kyuu - Wednesday, May 30, 2012 - link
Oh hai. You must be new to the human race. Marketing and "stretching the truth" have been synonymous since... forever. AMD is hardly exceptional in this regard. Stop believing anything any marketing department sells you, period.