In an announcement last week, IBM effectively extended Moore’s Law for at least another generation of chips, maybe two. This contradicts what leading vendors, including IBM, have been saying for years about the imminent diminishing returns of Moore’s Law, which postulated that chips would double in capacity every 18-24 months. Moore’s Law drove the price/performance curve the industry has been experiencing for the past several decades.
Click to enlarge, courtesy of IBM
The announcement, ironically, coincides with IBM’s completion of the sale of its semi-conductor fabrication business to GLOBALFOUNDRIES, which IBM paid to take the costly facilities off its hands. To pull off the 7nm achievement IBM ended up partnering with a handful of players including public-private partnership with New York State and joint development alliance with GLOBALFOUNDRIES, Samsung, and equipment suppliers. The team is based at SUNY Poly’s NanoTech Complex in Albany.
To achieve the higher performance, lower power, and scaling benefits promised by 7nm technology, the IBM researchers turned to two main innovations, the use Silicon Germanium (SiGe) channel transistors and Extreme Ultraviolet (EUV) lithography integration at multiple levels, in effect bypassing conventional semiconductor manufacturing approaches.
Don’t expect to see new systems featuring these 7nm chips very soon. The announcement made no mention of any timetable for producing commercial products based on this technology. As Timothy Prickett Morgan, who writes extensively on IBM POWER Systems technology observed: the use of silicon germanium for portions of the transistors cuts back on power consumption for the very fast switching necessary for improving circuit performance, and the circuits are etched using extreme ultraviolet (EUV) lithography. These technologies may be difficult and expensive to put into production.
In the meantime, IBM notes that microprocessors utilizing 22nm and 14nm technology run today’s servers, cloud data centers, and mobile devices; and already 10nm technology is well on the way to becoming a mature technology. The 7nm chips promise even more: at least a 50% power/performance improvement for next mainframe and POWER systems that will fuel the Big Data, cloud and mobile era, and soon you can add the Internet of Things too.
The z13 delivers unbeatable performance today. With the zEC12 IBM boasted of the fastest commercial chip in the industry, 5.5 GHz on a 32 nm wafer. It did not make that boast with the z13. Instead the z13 runs on a 22 nm core at 5 GHz but still delivers a 40% total capacity improvement over the zEC12.
It does this by optimizing the stack top to bottom with 600 processors and 320 separate channels dedicated just to drive I/O throughput. The reason for not cranking up the clock speed on the z13, according to IBM, was the plateauing of Moore’s Law. The company couldn’t get enough boost for the tradeoffs it would have had to make. Nobody seems to be complaining about giving up that one-half GHz. Today the machine can process 2.5 billion transactions a day.
The ride up the Moore’s Law curve has been very enjoyable for all. Companies took the additional processing power to build onto the chip more capabilities that otherwise would have required additional processors. The result: more performance and more capabilities at lower cost. But all good things come to an end.
This 7nm breakthrough doesn’t necessarily restore Moore’s Law. At this point, the best we can guess is that it temporarily moves the price/performance curve to a new plane. Until we know the economics of mass fabrication in the 7nm silicon germanium world we can’t tell whether we’ll see a doubling as before or maybe just a half or quarter or maybe it could triple. We just don’t now.
For the past decade, Morgan reports, depending on the architecture, the thermal limits of systems imposed a clock speed limit on processors, and aside from some nominal instruction per clock (IPC) improvements with each recent microarchitecture change, clock speeds and performance for a processor stayed more or less flat. This is why vendors went parallel with their CPU architectures, in effect adding cores to expand throughput rather than increasing clock speed to boost performance on a lower number of cores. Some, like IBM, also learned to optimize at every level of the stack. As the z13 demonstrates, lots of little improvements do add up.
Things won’t stop here. As Morgan observes, IBM Research and the Microelectronics Division were working with GLOBALFOUNDRIES and Samsung and chip-making equipment suppliers who collaborate through the SUNY Polytechnic Institute’s Colleges of Nanoscale Science and Engineering in nearby Albany to get a path to 10 nm and then 7 nm processes even as the sale of GLOBALFOUNDRIES was being finalized.
The next step, he suggests, could possibly be at 4 nm but no one is sure if this can be done in a way that is economically feasible. If it can’t, IBM already has previewed the possibility of other materials that show promise.
Moore’s Law has been a wonderful ride for the entire industry. Let’s wish them the best as they aim for ever more powerful processors.
Tags: System z, mainframe, IBM, Linux, Power Systems, Cloud, zEnterprise, analytics, Big Data, mobile, zEC12, technology, POWER8, Moore's Law, GLOBALFOUNDRIES, Samsung, Silicon Germanium (SiGe), Extreme Ultraviolet (EUV) lithography, 22nm, 14 nm, 7nm, instruction per clock (IPC), CPU