Testing the latest x86 rack servers and low power server CPUs
by Johan De Gelas on July 22, 2009 2:00 AM EST- Posted in
- IT Computing
Performance: Low Power CPUs Compared
The differences in performance are small, even insignificant, between the different servers. When it comes to comparing the servers, we'll focus on power consumption. When it comes to performance, we'll focus on the CPUs. We use our vApus Mark I benchmark as it has a mix of decision support (MS SQL Server), OLTP (Oracle), and web serving (PHP, IIS) on top of VMware's ESX 4.0. You can read a detailed description of our in-house developed benchmark here. We are working on an open source version to allow third parties to repeat our benchmarking.
We ran vApus mark I with one tile. Normally you'll see at least two tile (8 VMs) benchmarks in our server CPU tests unless we are limited by memory. As the amount of registered DDR3 memory available to us is at present 12 4GB DIMMs (48GB) and we had to fill a 4-server node Twin2 machine, we were limited to 12GB per node. Therefore, all testing is done with one tile or four VMs.
There's lots of interesting data here for the hardware loving professionals. It is the first time we have done such extensive testing on ESX 4.0, and we notice that while the Xeon X5570 and "Istanbul" Opteron 2435 are in line with our previous review, the quad-core "Shanghai" Opteron numbers are not (+6%). As in the previous review most of our attention was on the new AMD hex-core and its Xeon X5570 rival, so we did not double-check our Opteron 2384 numbers. If you compare them with our ESX 3.5 numbers, you'll see that quad-core Opteron is about 6% faster with ESX 4.0, while its six-core brother does not gain anything. As we use four vCPUs per VM, it is a lot harder for the ESX scheduler to do this efficiently on the six-core chip and that is most likely the reason why hex-core does not benefit from the ESX 3.5 to ESX 4.0 update.
Also interesting is that the Xeon "Nehalem" at 2.26GHz is capable of keeping up with the 2.9GHz Opteron "Shanghai". Remember, vAPUS Mark I is one of the benchmarks where AMD is at its best. In this best case for AMD, the Nehalem architecture is about 28% faster clock for clock. The Xeon E5504, the second slowest available Xeon "Nehalem", does not have Hyper-Threading (lose about 15%) or turbo boost (another ~5% loss) and only has 4MB of L3 cache. The result is that it is only 15% faster clock for clock than the Shanghai Opteron.
Also noteworthy is that one Xeon 2.93GHz performs as well as a dual Xeon at 2GHz and slightly better than a dual Opteron 2377 EE. If we tested with eight VMs, the dual machines would perform slightly better, while the single CPU system would stagnate. Still, that does not change the fact that a single socket server with a Xeon X5570 might be an interesting alternative to many dual socket servers if performance/watt matters.
Our performance conclusion is that the best Opteron EE is about as fast as the Xeon Nehalem at 2GHz. The L5520, Intel's lowest power "Nehalem" is as fast as the fastest 75W ACP Opteron at 2.9GHz. Next up are the power consumption numbers.
Facebook
Twitter
RSS
12 Comments
View All Comments
Doby - Thursday, July 23, 2009 - link
I don't understand why virtualization benchmarking is done with 16 or fewer VMs. With the CPU power of the newer CPU you can consolidate far more on there. Why aren't the benchmarks done with VMs with varying workloads, around 5% or less utilization, and then see how many VMs a particular server can handle. It would be far more real world.I have customers running over 150 VMs on a 4 CPU box, the performance compison of which CPU can handle 16 VMs better is completely bogus. It's all about how many VMs can I get without overloading the server (60-80% utilization).
JohanAnandtech - Thursday, July 23, 2009 - link
As explained in the article, we were limited with the amount of DDR-3 we have available. We had a total of 48 GB of DDR-3 and had to test up to servers. It should not be too hard to figure out what the power consumption could have been with twice or even four times more memory. Just add 5 Watt per DIMM.BTW, 150 VMs on one box is not extremely rare in the realworld. Are those VDI VMs?
"the performance comparison of which CPU can handle 16 VMs better is completely bogus"
On a dual socket machine it is not. Why would it be "bogus"? I agree that in a perfect world we would have loaded that machine up to 48 GB per Server (that is a fortune of 192 GB of RAM) and have run like 20-30 VMs per server. A little bit of understanding for the limitations we have to face would make my day....
uf - Thursday, July 23, 2009 - link
What power consumption is for low loaded server (not idle!) say at 10% and 30% average cpu utilization per core?MODEL3 - Wednesday, July 22, 2009 - link
in your comment:If AMD would apply the methodology of Intel to determine TDP they would end up somewhere between ACP and the current "AMD TDP"
You referring exclusively to the server CPUs?
Because if not, the above statement is false and unprofessional.
I don't have access to server CPUs but from my experience with mainstream consumer CPUs tells me the exact opposite:
65nm dual core (same performance level) 65W max TDP:
both 6420 (2,13GHz)& 4600 (2,4GHz) has lower* actual TDP than 5600 (2,9Ghz)
45nm dual core (same performance level) 65W max TDP:
both 7200 (2,53GHz)& 6300 (2,8GHz) has lower* actual TDP than Athlon 250 (3,0Ghz)
45nm Quad core (same performance level) 65W max TDP:
Q8200S (2,33 GHz) has lower* actual TDP than Phenom II 905e (2.5GHz)
I don't even need to give details for system configurations everyone knows these facts.
* not by much but nevertheless lower (so from that point to the point of " AMD has actual TDP somewhere between AMD's ACP and Intel's TDP " there is a huge gap
JohanAnandtech - Wednesday, July 22, 2009 - link
Correct. I only checked for server CPUs (see the pdf I linked).JarredWalton - Wednesday, July 22, 2009 - link
There are several issues at work, particularly with desktop processors. For one, AMD and Intel both have a range of voltages on desktop parts, so (just throwing out numbers) one CPU might run at 1.2V and another with the same part might run at 1.225V - it's a small difference but it can show up.Next, Intel and AMD both seem to put out numbers that are a theoretical worst case, and clock speed and voltage of a given chip help determine where the CPUs actually fall. The stated TDP on a part might be 65W, and with some 65W chips you can get very close to that while with others you might never get above 50W, but they'll both still state 65W.
The main point is that AMD's ACP ends up lower than what is realistic and their TDP ends up as essentially the worst-case scenario. (AMD parts are marketed with the ACP number, not TDP.) Meanwhile, Intel's TDP is higher than AMD's ACP but isn't quite the worst-case scenario of AMD's TDP.
I believe that's the way it all works out: Intel reports TDP that is lower than the absolute maximum but is typically higher than most users will see. AMD reports ACP that is more like an "average power" instead of a realistic maximum, but their TDP is pretty accurate. Even with this being the general case, processors are still released in families and individual chips can have much lower power requirements than the stated ACP/TDP - basically they should always come in equal to or lower than the ACP/TDP, but one might be 2W lower and another might be 15W lower and there's no easy way to say which it is without testing.
MODEL3 - Wednesday, July 22, 2009 - link
I mostly agree with what you 're saying except 2 things:1.AMD's TDP ends up as essentially the worst-case scenario (not true in all the cases e.g. Phenom X4 9350e (it has actual TDP higher than 65W)
2.In all the examples I gave, Intel & AMD had the same "official" TDP (also same more or less performance & same manufacturing proccess) so with your logic AMD should have lower than Intel actual TDP which is not true.
I live in Greece, here we pay 0,13€ (inc. VAT) per KW, so...
In another topic did you see the new prices for AMD Athlon II X2 245 (66$) & 240 (60$)? (while Intel 5300 cost 64$ & 5400 74$)
They should have priced them at 69$ & 78$.
No wonder why AMD is loosing so much money, they have to fire immediately those idiots who dit it (it reminds me the days before K8 when AMD used these methods)
JPForums - Wednesday, July 22, 2009 - link
I'm having a hard time correlating your chart and your assessment."Notice how adding a second L5520 CPU and three DIMMs of DDR3-1066 to our Chenbro server only adds 9W."
Found that one. However, on the previous page you make this statement:
"So adding a Xeon X5570 adds about 58W (248W - 175W - three DIMMs of 5W), while adding an Opteron 2435 2.6GHz adds about 47W (243 - 181 - three DIMMs of 5W)."
This implies to me that just adding the 3 DIMMs should have raised the power 15W.
"Add an Opteron EE to our AMD server and you add 22W."
Check. Did you add the 3 DIMMs here as well?
"The result is that the best AMD platform consumes about 20W more than the best Intel platform when running idle."
Can't find this one. There are 3W difference between the Xeon L5520 and the Opteron 2377 EE. There are 16W difference for the dual CPU counter parts (closer). All the other comparisons leave the Intel platform consuming more power than the AMD counterpart. Is this supposed a comparison of the platform without the CPU? It is unclear to me given the words chosen. I was under the impression that the CPU is generally considered part of the platform.
"Intel's power gating is the decisive advantage here: it can turn the inactive cores completely off. Another indication is that the dual Opteron 2435 consumes about 156W when we turn off dynamic power management, which is higher than the Xeon X5570 (150W)."
An explanation of dynamic power management would be helpful. It sounds like you're saying that Intel's power management techniques are clearly better because when you turn both their power management and AMD's power management off, the Intel platform works better. The only way your statements make sense is if the dynamic power management you are talking about isn't a CPU level feature like clock gating. In any case, power management techniques are worthless if you can't use them.
As a side question, when the power management support issue with the Xeon X5570 is addressed and AMD has a new lower power platform, where do you predict the power numbers will end up? I'd still expect the "Nahalem" Xeons to win in performance/power, though.
JohanAnandtech - Wednesday, July 22, 2009 - link
Part 2 :-)"The result is that the best AMD platform consumes about 20W more than the best Intel platform when running idle."
Can't find this one. "
135W - 119W = 16W. I made a small error there (spreadsheet error).
"It sounds like you're saying that Intel's power management techniques are clearly better because when you turn both their power management and AMD's power management off, the Intel platform works better. "
More or less. There are two ways the CPU can save power: 1) lower voltage and clockspeed or 2) Shut down the cores that you don't need. In case of the Intel part, it is better at shutting down the cores that it don't need. They simply are completely shut off and consume close to 0 W. In case of AMD, each core still consumes a few watt.
So if you turn Speedstep and power now! off, you can see the effect of the 2nd way to save power. It confirms our suspicion of why the Opteron EE is not able to beat the L5520 when running idle.
JohanAnandtech - Wednesday, July 22, 2009 - link
I'll chop my answers up to keep these comments readable.quote:
"Notice how adding a second L5520 CPU and three DIMMs of DDR3-1066 to our Chenbro server only adds 9W."
Found that one. However, on the previous page you make this statement:
"So adding a Xeon X5570 adds about 58W (248W - 175W - three DIMMs of 5W), while adding an Opteron 2435 2.6GHz adds about 47W (243 - 181 - three DIMMs of 5W)."
This implies to me that just adding the 3 DIMMs should have raised the power 15W. "
No. Because the 9W is measured at idle. It is too small to measure accurately, but DIMMs do not consume 5W per DIMM in idle. Probably more like 1W or so.