components that are extra components on an Intel motherboard are built into the X-Gene chip. No network interface card is needed on an X-Gene motherboard, because it's been etched in. Likewise, no I/O controller or SATA storage controller is needed; they're also already there.
That makes the X-Gene server less greedy for power and allows densely packed ARM servers to run cooler, all of which reduces their total cost of ownership, Singh said.
The chip was also designed with hefty network bandwidth and data flow channels. It has four memory channels for loading data and 40 Gbit/s networking capacity. The chip is designed to run at a 2.4 GHz frequency, roughly equivalent to low-end Sandy Bridge editions.
Comparing chips' performance is a notoriously difficult task. Multi-threaded server chips can outshine standard PC chips at certain number-crunching tasks, then look mediocre in a more routine job. Singh said he would show during the Icehouse demo Friday that the open-source Xen hypervisor performs well on X-Gene servers. He will use figures he got from Citrix, one of the 29 members of the Linaro project, that indicate the ARM chip runs Xen with only 1% of the processor used by the hypervisor itself. A more typical figure on x86 chips is 2% or 2.5%, said Singh.
Singh said he was told that the performance gain probably results from the port of Xen to ARM that was able to leave behind "crud" or little-used code in the x86 version. Xen compiled for x86 and other x86 software may include code for earlier versions of the x86 instruction set, given the architecture's many iterations and long history. Compilations for X-Gene need to be compatible only with the first version of the chip. Nevertheless, if that performance advantage can be clearly established, X-Gene's reputation for efficient execution will have a better chance of being established.
Singh claimed that use of Applied Micro ARM-based servers could reduce the cost of server ownership by 50% over three years and 70% over years of operation, due to the lower purchase price and power savings.
Such savings may turn out to be pie in the sky, if there are hidden costs in faulty conversions of x86 software to ARM or other unforeseen expenses. But for Singh in Taiwan, a moment of truth has arrived. Not only is ARM ready for servers, it is ready for banks of them in the cloud, and he's hoping a demonstration of OpenStack on X-Gene will prove it.
Could the growing movement toward open-source hardware rewrite the rules for computer and networking hardware the way Linux, Apache, and Android have for software? Also in the Open Source Hardware issue of InformationWeek: Mark Hurd explains his "once-in-a-career opportunity" at Oracle.