The Opteron 6276: a closer look
by Johan De Gelas on February 9, 2012 6:00 AM EST- Posted in
- IT Computing
- CPUs
- Bulldozer
- AMD
- Opteron
- Cloud Computing
- Interlagos
Benchmark Configuration
Since AMD sent us a 1U Supermicro server, we had to resort to testing with our 1U servers again. That is why we went back to the ASUS RS700 for the Xeon server.
Supermicro A+ server 1022G-URG (1U Chassis)
| CPU |
2x AMD Opteron Interlagos 6276 (2.3GHz, 8 cores per CPU, 16 integer clusters) 2x AMD Opteron Interlagos 6220 (3.0GHz, 4 cores per CPU, 8 integer clusters) 2x AMD Opteron Magny-Cours 6174 (2.2GHz, 12 cores per CPU) |
| RAM | 64GB (8x8GB) DDR3-1600 Samsung M393B1K70DH0-CK0 |
| Motherboard | SuperMicro H8DGU-F |
| Chipset | AMD Chipset SR5670 + SP5100 |
| BIOS version | v2.81 (10/28/2011) |
| PSU | SuperMicro PWS-704P-1R 750Watt |
The AMD CPUS have four memory channels per CPU. The new Interlagos Bulldozer CPU supports DDR3-1600 and thus our dual-CPU configuration uses eight DIMMs for maximum bandwidth and performance. We ran with one DIMM per channel.
Asus RS700-E6/RS4 1U Server
| CPU | 2x Intel Xeon X5650 (2.66GHz, 6 cores/12 threads) |
| RAM | 48GB (12x4GB) Kingston DDR3-1333 FB372D3D4P13C9ED1 |
| Motherboard | Asus Z8PS-D12-1U |
| Chipset | Intel 5520 |
| BIOS version | 1102 (08/25/2011) |
| PSU | 770W Delta Electronics DPS-770AB |
To speed up testing, we ran the Intel Xeon and AMD Opteron system in parallel. As we didn't have more than eight 8GB DIMMs, we used our 4GB DDR3-1333 DIMMs for the Xeon server. The Xeon system only ends up with 48GB, but this is no disadvantage as our benchmark with the highest memory footprint (Nieuws.be/SQL Server 5 tiles) uses no more than 30GB of RAM.
We measured the difference between 12x4GB and 8x8GB of RAM and recalculated the power consumption for our power measurements (note that the differences were very small). There is no practical alternative as our Xeon has three memory channels and cannot be optimally configured with the same amount of RAM as our Opteron system (which has four channels).
We chose the Xeons based on AMD's positioning. The Xeon X5649 is priced at the same level as the Opteron 6276 but we didn't have the X5649 in the labs. As we suggested in our previous article, the Opteron 6276 should reach the performance of the X5650 to be attractive, so we tested with the X5650.
Common Storage System
Both servers used intel 710 SSDs for storing the database.
Software configuration
All Windows testing was done on Windows 2008 R2 SP1. The Linux tests are done on Ubuntu 11.10 Linux kernel 3.0.0-14 SMP x86_64.
Other
Both servers were fed by a standard European 230V (16 Amps max.) powerline. The room temperature was monitored and kept at 23°C by our Airwell CRACs. We used the Racktivity ES1008 Energy Switch PDU to measure power. Using a PDU for accurate power measurements might seem pretty insane, but this is not your average PDU. Measurement circuits of most PDUs assume that the incoming AC is a perfect sine wave but it never is. However, the Rackitivity PDU measures true RMS current and voltage at a very high sample rate: up to 20,000 measurements per second for the complete PDU.
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Scali - Friday, February 10, 2012 - link
No, because if you read the ENTIRE benchmark configuration page, you'd see that all the AMD systems had 2 CPUs as well.Scali - Saturday, February 11, 2012 - link
Oh, and while we're at it... the Intel system had only 48 GB of 1333 memory, where the AMDs had 64 GB of 1600 memory.(Yes, Bulldozer is THAT bad)
PixyMisa - Saturday, February 11, 2012 - link
Or rather, MySQL scales that poorly.What we can tell from this article is that if you want to run a single instance of MySQL as fast as possible and don't want to get involved with subtle performance tuning options, the Opteron 6276 is not the way to go.
For other workloads, the result can be very different.
JohanAnandtech - Saturday, February 11, 2012 - link
Feel free to send me a suggestion on how to setup another workload. We know how to tune MySQL. So far none of these settings helped. The issue discussed (spinlocks) can not be easily solved.Scali - Saturday, February 11, 2012 - link
I'm not sure if you bothered to read the entire article, because MySQL was not the only database that was tested.There were also various tests with MS SQL, and again, Interlagos failed to impress compared to both Magny Cours-based Opterons and the Xeon system.
JohanAnandtech - Saturday, February 11, 2012 - link
The clockspeed of the RAM has a small impact here. 64 vs 48 GB does not matter.Scali - Saturday, February 11, 2012 - link
Not saying it does... Just pointing out that the AMD system had more impressive specs on paper, yet failed to deliver the performance.JohanAnandtech - Saturday, February 11, 2012 - link
Again, it is not CMT that makes AMD's transistor count explode but the combination of 2x L3 caches and 4x 2M L2-caches. You can argue that AMD made poor choices concerning caches, but again it is not CMT that made the transistor count grow.I am not arguing that AMD's performance/billion transistors is great.
Scali - Saturday, February 11, 2012 - link
I think you are looking at it from the wrong direction.You are trying to compare SMT and CMT, but contrary to what AMD wants to make everyone believe, they are not very similar technologies.
You see, SMT enables two threads to run on one physical core, without adding any kind of execution units, cache or anything. It is little more than some extra logic so that the OoOE buffers can handle two thread contexts at the same time, rather than one.
So the thing with SMT is that it REDUCES the transistorcount required for running two threads. By nearly 100%.
CMT on the other hand does not reduce the transistorcount nearly as much. So if you are merely looking at an 'exposion of transistor count', you are missing the point of what SMT really does.
Other than that, your argument is still flawed. Even an 8-thread Bulldozer has a higher transistor count than the 12-thread Xeon here. It's not just cache. CMT just doesn't pack as many threads per transistor as SMT does... and to make matters worse, CMT also has a negative impact on single-threaded performance (which again, if you are looking at it from the wrong direction, may look like better scaling in threadcount... but effectively, both with low and high threadcounts, the Xeon is the better option... and this is just a midrange Xeon compared to a high-end Interlagos. The Xeon can scale to higher clockspeeds, improving both single-threaded and multithreaded performance for the same transistorcount).
So what your article says is basically this:
CMT, which is nearly the same as having full cores, especially in integer-only tasks such as databases, since you have two actual integer cores, has nearly the same scaling in threadcount as conventional multicore CPUs.
Which has a very high 'duh'-factor, since it pretty much *is* conventional multicore.
It does not reduce transistorcount, nor does it improve performance, so what's the point?
JohanAnandtech - Friday, February 10, 2012 - link
Semantics :-). I can call it a core with CMT, or a module with 2 cores. Both are valid.