Sips juice like an iPad
The X-Gene design is aimed to make a server more like an iPad, with idle power of under 500 milliwatts per core and sleep mode of 300 milliwatts; active power is expected to be around 2 watts per core.
The chip will also have dynamic frequency scaling – what is generally called a turbo-boost mode – that allows the clock speed of the chip to be goosed when a job needs faster single-thread performance and there is enough spare thermal capacity to allow a core to run hot for a bit. Moreover, server vendors who adopt the X-Gene chip will be able to set the thermal design point and clock speeds in the chips to meet performance requirements and make the heat tradeoffs – and lock those TDP settings in.
But wait, there's more. The X-Gene has a fully non-blocking, 1Tb/sec interconnect, which can be used to feed data between multiple X-Gene sockets at 100Gb/sec speeds, and that provides nearly 80Gb/sec of aggregate bandwidth.
Here's the interesting bit: this non-blocking fabric allows an X-Gene server to scale from 2 to 128 cores in a fully cache coherent server image. So not only can the X-Gene be set up to be a baby symmetric multiprocessing server inside of a single chip, that SMP can be extended across multiple X-Gene chips – and in a glueless fashion that does not require extra chips.
The X-Gene chip also has on-chip CPU and I/O virtualization, just like x86, Sparc, Power, and Itanium chips do. The architecture also allows for various kinds of offload engines to be plugged in and perhaps integrated on the chip package.
The chip is not yet ready, but Applied Micro has cooked up a board that simulates 128 cores and all the I/O features, and that can run Fedora or Ubuntu Linux; it's powered by a bunch of Vertex FPGAs, and is show below:
The X-Gene simulation boards will be ready for partners in January 2012, and Applied Micro expects to have early silicon available for the real X-Gene chip in the second half of 2012 – that's anywhere from a year and a half to two years ahead of when ARM Holdings expects for prototypes of the ARMv8 to appear in systems based on its own reference designs. Applied Micro is smart enough to know that the server industry can't wait that long for a 64-bit chip, even if smartphones and tablets can.
Applied Micro has tapped Taiwan Semiconductor Manufacturing Corp as its foundry for the X-Gene chips, and will first etch the chips in its 40 nanometer processes, then follow-up with kickers using TSMC's 28nm processes. It seems likely that at the 28 nanometer node Applied Micro will significantly boost the X-Gene core count, maybe to four cores and maybe as many as six or eight. ®
Ok, I confess
I want one... or two but certainly no more than 128. Well, for now anyway.
"Intel can use their design expertise and fabrication to make an ARM that Texas, Samsung or Qualcomm can't compete with. Maybe they already have a skunkworks team and should add all the Itanium resources to it."
Perfectly true. But what would be the point? Intel haven't had any real success outside x86 in the last couple of decades, why would that be about to change?
"the only Itanium customer, HP, is flirting with ARM based servers"
People that buy Itanium buy it despite IA64 not because of IA64. They buy it either because they need ultra-massive single-image SMP systems of a kind that AMD64 still can't quite deliver, or because their software stack needs an OS that HP choose not to port off IA64 (HP-UX, VMS, NSK). That situation won't last forever.
"Intel can use their design expertise and fabrication to make an ARM that Texas, Samsung or Qualcomm can't compete with."
Yes they could easily do that. But that would mean that Intel are just another supplier in amongst a whole host of others. Intel's wafer baking expertise would mark them out though.
However, I'm pretty sure that Intel are desperate for the world to stay with x86 for servers, because then they'd keep the whole thing to themselves. At the moment they have only AMD to contend with. In the ARM market there's hundreds of other companies to compete against, and it would be difficult to dominate them all.
The moment Intel start fabbing ARMs will signify that they've finally admitted that x86 is a crappy, out of date architecture. That would really make them wince, especially as it would be an admission to their shareholders that the game is up, the big days are over.