Sun's Sparc server roadmap revealed
Well, what's left of it
Please help me. I'm falling...
That leaves us with the Niagara family of chips, known as the Sparc T series outside of Sun and used in entry and midrange servers. El Reg has already told you about the faster Niagara-2+ (T2) and Victoria Falls+ (T2+) processors that received clock speed boosts in July.
A few weeks ago, at the Hot Chips 21 conference, Sun talked very generally about the 16-core "Rainbow Falls" Sparc T series processor, which is known variously as the Niagara-3 and the KT chip if you are having trouble keeping track. It looks like this future Sparc T chip has been changed a few times. Back in June 2008, El Reg learned that this future Niagara family chip would sport 16 cores and 16 threads per core, for a total of 256 threads per socket.
That's as many threads as Sun can cram into a four-socket T5440 server today using its Sparc T2+ chips. The servers based on this chip were supposed to scale to as high as eight sockets in a single system image, for a total of 2,048 threads. When Sun talked about Rainbow Falls at Hot Chips at the end of August, it said the chips would have 16 cores but didn't specify the thread count, like you do on sheets. The cryptographic accelerators that Sun talked about in a separate presentation said that they had eight "strands," and I didn't see that this also meant that the next generation of Sparc T chips would only have eight threads per core, just like the T2 and T2+ already do.
What we learn from the Sparc roadmap above is that not only has Sun cut back on the threads with Rainbow Falls, it has also cut back on the socket count, keeping it at the same four sockets used by the T5440 server. And instead of hitting something close to 2 GHz as it should be able to do as it shifts from a 65 nanometer to a 45 nanometer process in the middle of 2010, Sun is only telling customers that it can boost clock speeds to 1.67 GHz with Rainbow Falls.
This, to use a technical term in the computer business, sucks.
With the "Yosemite Falls" kicker to the T3 chip, presumably to be sold as the T4, Sun is planning to implement a new core for the Niagara family, and it will backstep to eight cores with eight threads per core. If you are thinking this is necessary to boost clock speeds, you are right, since this chip will use the same 40 nanometer process as Rainbow Falls T3s and will run at 2.5 GHz. However, the SMP scalability of the chip will still be limited to a paltry four sockets.
In the middle of 2012, something interesting is on the roadmap, a chip code-named "Yellowstone Falls", which has only four cores and eight threads per core that runs at 3 GHz. This chip will be implemented in a 28 nanometer process and will be used in servers that span from 4 to 192 sockets. (Yes, I said 192, as you can see from the pretty picture). At the end of 2012, there is a related chip called "Cascade Falls" that runs at the same 3 GHz and has 16 cores and eight threads per core like the future Rainbow Falls T3 chips, but it can be used in machines with anywhere from 1 to 8 processor sockets.
All of this is subject to change, and some of it most certainly will once Oracle takes control of Sun. ®