AMD's 12-core "Magny-Cours" Opteron 6174 vs. Intel's 6-core Xeon
by Johan De Gelas on March 29, 2010 12:00 AM EST- Posted in
- IT Computing
Power Consumption
The Magny-Cours Opteron arrived one week ago, which is barely enough time to do virtualization benchmarking. So we have to postpone extensive power testing to a later date. The Opteron 6174 came in a desktop reference system which is in no way comparable to our Xeon X5670 1U server. We do have an six-core Opteron based system which is very similar to the Opteron 6174 reference system: the motherboard is also equipped with the new AMD SR5670 chipset and housed in the same desktop system. We can tell you that the idle power of the Opteron 6174 is a few watts lower than the six-core Opteron 2435. Both throttle back to 800 MHz, but the Opteron 6100 series gets a real C1E mode.
C1E mode can only be entered if all CPUs are idle. In a dual socket system, both CPUs enter C1E or they don’t. C1E mode is entered only after longer periods of inactivity. All cores flush their L1 and L2 caches to the L3-cache. Then all cores are clockgated (C1). Once that happens, the Hyper Transport links are put in a lower power state. This allows the chipset to enter a lower power state as well. Only when all these previous steps are done, both sockets are in C1E. DMA events will make the sockets go out of the C1E state. So C1E probably won't happen much on server systems. The C1E state is only entered if absolutely no processing is happening at all.
The C1E mode can reduce power quite a bit:
- Core clocks are turned off (Clockgate C1 state)
- L3, North Bridge, and memory controller all divide their clock frequencies (but are not clockgated!)
- All HyperTranspor links transition to LS2 low power state (LDT_STOP_L)
- DRAM DLL’s disabled
- Memory Transitions from precharge power down mode to self refresh mode (low power)
According to AMD, at full load a 1.7GHz 65W ACP Opteron 6164 HEwould consume about 4% more power than a 2.1 GHz 55W ACP 6-core Opteron 2425 HE. AMD measured 225W for the former, 215W for the latter. We measured 263W on the same system at full load with an Opteron 6174. That's 48W more, or about 24W per CPU. Assuming that the low power CPUs were running at their ACP (65W), we can conclude that the 2.2 GHz Magny-Cours needs about 89W. While the new twelve-core Opteron clearly needs a bit more power than the six-core Opteron, it's not a dramatic increase.
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zarjad - Friday, April 2, 2010 - link
I understand that HT can be disabled in BIOS and that some benchmarks don't like HT.elnexus - Wednesday, April 21, 2010 - link
I can report that one of my customers, performing intensive image processing, found that DISABLING hyper-threading on a Nehalem-based workstation, actually IMPROVED performance considerably.It seems that certain applications don't like hyper-threading, while others do. I always recommend that my customers perform sensitivity analyses on their computing tasks with HT on and off, and then use whichever is best.
tracerburnout - Wednesday, March 31, 2010 - link
How is it possible that Intel's Xeon X5670 rig returns 19k+ for a score while AMD's magny-cours returns only 2k+?? I only question the results of this benchmark chart because Intel's Xeon X5570 rig returns only around 1k. How can a X5670 be 19x faster than a X5570?? And I doubt the same is true for the magny-cours by being just 10.5% of what the X5670 can do.(is there an extra '0' by accident in there?)
tracerburnout
proud supporter of AMD, with a few Intel rigs for Linux only
JohanAnandtech - Thursday, April 1, 2010 - link
No, it is just that Sisoft uses the new AES instructions of West-mere. It is a forward looking benchmark which tests only a small part of a larger website code base. So that 19x faster will probably result in 10 to 20% of the complete website being 19x faster. So the real performance impact will be a lot slower. It is interesting though to see how much faster these dedicated SIMD instructions are on these kinds of workloads.alpha754293 - Thursday, April 1, 2010 - link
If you guys need help with setting up or running the Fluent/LS-DYNA benchmarks let me know.I see that you don't really spend as much time writing or tweaking it as you do with some of the other programs, and that to me is a little concerning only because I don't think that it is showing the true potential of these processors if you run it straight out-of-the-box (especially with Fluent).
Fluent tends to have a LOT of iterations, but it also tends to short-stroke the CPU (i.e. the time required to complete all of the calculations necessary is less than 1 second and therefore; doesn't make full use of the computational ability.)
Also, the parallelization method (MPICH2 vs. HP MPI) makes a difference in the results.
You want to make sure that the CPUs are fully loaded for a period of time such that at each iteration, there should be a noticable dwell time AT 100% CPU load. Otherwise, it won't really demonstrate the computational ability.
With LS-DYNA, it also makes a difference whether it's SMP parallelization or MPP parallelization as well.
k_sarnath - Friday, April 2, 2010 - link
The most baffling part is how linux could engage 12-CPUs much better than windows. I am obviously curious about the OS platform for other tests.. Similary MS SQL was able to scale well on multi-cores... In this context, I am not sure how we can look at the performance numbers... A badly scaling app or OS could show the 12-core one in bad light.OneEng - Saturday, April 3, 2010 - link
Hi Johan,I have followed your articles from the early day's at Ace's and have a good respect for the technical accuracy of your articles.
It appears that the X5570 scaling between 4 and 8 cores has very little gain in the Oracle Calling Circle benchmark. Furthermore, the 24 cores of MC at 2.2Ghz are way behind. Westmere appears to do quite well, but really should not be able to best 8 cores in the X5570 with all else being equal.
I have heard some state that the benchmark is thread bound to a low number of threads (don't know if I am buying this), but surely something fishy is going on here.
It appears that there is either a real world application limit to core scaling on certain types of Oracle database applications (if there are, could you please explain what features an app has when these limits appear), or that the benchmark is flawed in some way.
I have a good amount of experience in Oracle applications and have usually found that more cores and more memory make Oracle happy. My experience seems at odds with your latest benchmarks.
Any feedback would be appreciated .... Thanks!
JohanAnandtech - Tuesday, April 6, 2010 - link
I am starting to suspect the same. I am going to dissect the benchmark soon to see what is up. It is not disk related, or at least that surely it is not our biggest problem. Our benchmark might not be far from the truth though, I think Oracle really likes the big L3-cache of the Westmere CPU.If you have other ideas, mail at johanATthiswebsiteP
heliosblitz2 - Wednesday, April 7, 2010 - link
You wroteTest-Setup:
Xeon Server 1: ASUS RS700-E6/RS4 barebone
Dual Intel Xeon "Gainestown" X5570 2.93GHz, Dual Intel Xeon “Westmere” X5670 2.93 GHz
6x4GB (24GB) ECC Registered DDR3-1333
"Also notice that the new Xeon 5600 handles DDR3-1333 a lot more efficiently. We measured 15% higher bandwidth from exactly the same DDR3-1333 DIMMs compared to the older Xeon 5570."
That is not exactly the reason, I think.
The reason ist you populated the second memory-bank in both setups.
Intel specification:
Westmere-1333MHZ-CPUs run with 1333 MHZ with second bank populated while
Nehalem-1333MHZ-CPUs run with 1066 MHZ with second bank populated
That could be updated.
Compare tech docs on Intel site: datasheet Xeon 5500 Part 2 and datasheet Xeon 5600 Part 2
Arnold.
gonerogue - Saturday, April 10, 2010 - link
The Viper is a V10 and most certainly not a traditional muscle car ;)