There was an interesting article at Reuters about the upcoming Power7 CPU. I don´t want to talk about the point, that his announcement was well times to our announcement about the 1.6 GHz. I don´t want to talk about the announcement, that systems will be available in 2010 when you take into consideration, that the last rollout of Power6 took almost a year.
No, i want to hint you on an interesting fact in this article. But at first you should take into consideration that IBM tries to tell the world, that per core performance is the most important factor at all. Now look at the following paragraph the Reuters article:
It also said POWER7 will be more efficient than the POWER6, which was launched in May 2007, capable of two to three times performance while using the same amount of energy.
Two to three times the performance … sounds nice. Well … it doesn´t sound that nice, when you do some math on the numbers. Let´s assume the Power6 is a 2-core system. Let´s further assume, that Power7 is a 4 core architecture. Then Power7 delivers the same performance per core than Power6 … just more cores. Nice, but nothing earthshattering. But it gets even more interesting. Back in July 2008 Ashlee Vance wrote in the Register about Power7:
IBM looks set to join the seriously multi-core set with the Power7 chip. Internal documents seen by The Register show Power7 with eight cores per processor and also some very, very large IBM boxes based on the chip.
Okay, let´s do the same math again: Let´s assume the Power6 is 2-core, let´s further assume that Power7 is a 8-core design. Obviously a single core of the Power7 has just half the performance of the Power6 core. Hey, that will be interesting talks for the IBM sales people explaining that they were incorrect with the assumption that speed per core is the only interesting metric.