Calxeda's ARM server tested
by Johan De Gelas on March 12, 2013 7:14 PM EST- Posted in
- IT Computing
- Arm
- Xeon
- Boston
- Calxeda
- server
- Enterprise CPUs
Measuring Bandwidth
Stream measures "sustainable memory bandwidth" and is thus a good indication of how a CPU will handle data intensive applications. Dr. John McCalpin is the developer and maintainer of the STREAM benchmark.
We compiled with gcc 4.7 on all platforms and used the -O3 -fopen -static settings. It is important to remark that this version of gcc has been optimized by the Linaro group, a non-profit software engineering effort. Linaro's objective is to optimize the kernel and typical tools for the ARM-Cortex A-series CPUs.
On the Intel CPUs we force the threads to make use of Hyper-Threading with taskset. So for example, the four threads measurement is done on two physical cores with four threads. This gives an idea of how a quad-core ARM server node compares to a virtual machine that gets a few physical and few logical cores from the hypervisor. It also allows us to evaluate how two threads on top of an Atom core compare to two ARM cores. When you compare CPUs with similar power consumption, you typically get two ARM cores for each Hyper-Threaded Atom core.
The ARM based server is a pretty bad choice right now for memory intensive workloads. Even with four cores and DDR3-1333, the useable bandwidth is less than one sixth of what one Xeon core can sustain.
In a similar vein, the ECX-1000 is not capable of providing more bandwidth than an Atom system equipped with DDR2-667. However, both the Atom and ARM cores are pretty bad when it comes to bandwidth. Although the specs claim that the CPUs can drive one channel of DDR3-1066, the measured bandwidth comes nowhere near the theoretical 8.5GB/s that such a DIMM can deliver.
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Madpacket - Wednesday, March 13, 2013 - link
And all of a sudden AMD's acquisition of SeaMicro is starting to make sense. Thanks Johan, great article!JohanAnandtech - Wednesday, March 13, 2013 - link
I really really hope they downscale the current SeaMicro's soon. Because with a starting price at $139000, they are not catering to the typical SME :-).joshv - Wednesday, March 13, 2013 - link
It seems this has a very narrow application in VM hosting, but I am not sure it's applicable when you have the choice of just scaling up memory or process usage of the single instance Xeon server. For example, I could load 24 instances of my production middle tier on the ARM server - or I could run one instance on a Xeon server and give it all the memory and make sure it spawns enough threads to keep all the internal cores busy. Perhaps my middle tier software has issues with handling all that RAM, so maybe I run 4 instances of it as a process, not a biggy.I am going to bet that the Xeon server will win as it won't have the VM overhead.
Kurge - Wednesday, March 13, 2013 - link
I would be interested in a bare metal comparison. Since you're serving up the same app why would you split it between 24 VMs on the Xeon server? It's a bit contrived.Just load up Server 2012 and IIS or Linux + Apache straight up on the Xeon and see how it performs.
MrSpadge - Wednesday, March 13, 2013 - link
Very interesting!I'd prefer a fat machine with virtualized servers to get automatic load balancing, but it's not like one couldn't shuffle tasks around in the ARM farm. And there's room for improvement: be it the next Atom or the memory controller in the current ECX-1000 CPUs. And take a look at how badly they scale from 2 to 4 threads - surely, there's lot's of rooms left!
rubyl - Wednesday, March 13, 2013 - link
What is the average CPU utilization for the Viridis nodes and for the Xeon system under the 5 different concurrency loads (for the 24 webserver workload)?gercho - Wednesday, March 13, 2013 - link
When you said " The next generation ARM servers are already on the way and will probably hit the market in the third quarter of this year. The "Midway" SoC is based on a 28nm (TSMC) Cortex-A15 chip. A 28nm A15 offers 50% higher single-threaded integer performance at slightly higher power levels and can address up to 16GB of RAM." As far as I know the A15 cores have 50% more performance but consume 3X more power, that's not "slightly".........nofumble62 - Wednesday, March 13, 2013 - link
50% more performance at 3X more power... reminding me of the Netburst architect.thenewguy617 - Wednesday, March 13, 2013 - link
Can you please point me to sources of your number?Thanks
Wilco1 - Thursday, March 14, 2013 - link
Where on earth you do get that 3x from? So far no 28nm Cortex-A15 chips have been released. The A15 in the Exynos Octo uses about 1.25W per core at 1.8GHz according to Samsung. That's slightly more power than a Calxeda A9 uses per core, but the A15 gives twice the performance per core.