IBM's Power6+ Confusion

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ibmThe Register’s Timothy Prickett Morgan has written up a detailed account  of the last 18 months of IBM Power6 silicon goodness.  IBM went through a major processor roadmap upgrade to the Power series back in 2007.  Early roadmap slides showed the release of a Power6 processor base, then a significant upgrade to the platform in 2009.  The 2009 upgrade was said to include cores clocking in at 3.5GHz to 5GHz, with the expectation of a Power7 not far down the road. So where’s the discrepancy?

Rewind to October 2008.  IBM was fast on their way to delivering the latest bump to the Power6 line.  In rolling out the new batch of silicon for test, they quickly discovered that the new 65nm copper/SOI process and new instructions could enable one to clock a Power6 upwards of 5GHz.  Wait a second!?  We weren’t supposed to hit these speeds until 2009!  So, was the processor upgrade announced in October actually the Power6+?

We are continuing to take share and we didn’t need to highlight performance,” [Karl] Handy [VP of Marketing and Strategy for the Power Systems Division] explained in reference to the decision to not admit that some of the October machines were based on Power6+ chips. “We do think that more of the value in our Power Systems is coming from the Power software stack.”

According to the article, there is one important disctinction between the P6 and P6+.  The P6 includes a total of eight memory keys, the plus version contains sixteen.  According to the IBM docs, the additional memory keys “help prevent accidental memory overwrites that could cause critical applications to crash.”  No official word on whether the P6+ will eventually include another clock boost.

There’s lots of activity within the Power Systems Division at IBM.  The Power7 is scheduled to run on a 45nm platform at release sometime in 2010.  In the mean time, read Tim’s full account of the confusion here.