When comparing fruit, everyone knows not to compare apples to, say, an orange or, god forbid, a cumquat. The same applies to chips. See this nice article, then come back and read on…
Nice job, DELL. Ditto Intel! Now, you might think, “oh wow! A 20 watt Intel Server! ARM’s lead certainly didn’t last long; Calxeda is toast! ” A sub-20 watt Xeon is indeed an accomplishment; Intel is a great company and knows what they are doing. But be careful when comparing our 3.8 (ok, call it 4) watt ECX-1000 to a Xeon. On the surface, we consume 1/5th the power. Not bad! But the story runs deeper than that. Let’s dissect the fruit and see what’s inside.
Xeon is not an SoC (more on that in another blog). It is a multi-core processor, like the Cortex A9 from ARM. It does have some integrated I/O (PCI-E 3.0 to be precise). But it does not have Ethernet, much less five 10Gigabit Ethernet ports. It does not have SATA controllers. It does not have an integrated BMC for processor management, much less fabric management and power optimization. All of these need to be added as additional components in the system BOM cost and power envelope to offer equivalent and necessary functionality to a Calxeda ECX-1000. Xeon does have more performance per thread; probably 3-5X, in fact, depending on the workload. But remember that ARM processors for servers are NOT about performance. If you need performance, buy Intel, or AMD, or IBM Power. But, it doesn’t matter how fast your thread or core can run if you are spending 90% of your time waiting for I/O. And that is exactly the problem people have with traditional architectures today in dealing with data-intensive computing such as Hadoop.
What really matters is the total power and cost of a CLUSTER for a particular workload. Not a processor, or even an SoC. A cluster of Calxeda server nodes will consume only 5 watts each, complete with DRAM memory. At 100%. At idle it only consumes .5 watts. (Oh, yeah, don’t forget about memory which can consume as much as 1Watt per Gigabyte in traditional servers!)
So, always be sure to check your fruit carefully!