Sunday, March 22, 2009

Intel Core i7, Part 3 : Power management

As the title of this post said, I will not talk about required electrical power to sue the processor nor what kind of power management feature it has since there is not much new except in the Turboboost technology. Instead, I'll talk about calculation power. What make those CPUs as fast as they are. You know... processing power management.

Super powers
Yes, those new processors are really fast but what about their super powers? You didn't know, didn't you? Intel made a deal with some super heros to provide the new Core i7 with super powers like :
  • Turboboost Technology - A real-time dynamic, per core, overlocking technology.
  • Wide Dynamic Execution - A technology that enable to dispatch up to 4 instructions per clock cycle per processing unit.
  • Hyperthreading - An other technology that enable the system to fetch up to two times more instruction in the processor.
  • Integrated memory controller - Help pushing data real fast into the processor.
  • Advanced Smart Cache - Cutting in fourth the time it take to do about every memory access.

Power at work
Those technologies give a big boost at speed make the processor way more powerful than before. Let's start with the first one, Turboboost. It analyze, in real time, which core is idle and which are overloaded. It then cut off power to those who doesn't need it and reroute it to the one that are struggling by overclocking them for up to 30% of their original speed. This technology gives a big performance boost for single threaded application that does not benefit from additional core's presence. The second one, Wide Dynamic Execution, is a technology that will peek at your processor activities using techniques like data flow analysis, speculative execution, out of order execution, and super scalars to execute up to 33% more instructions per clock cycle on each core than before. On older Intel architecture and AMD Phenom architecture, the processor could only handle 3 instructions in the same clock cycle. This technology push that to four and will help on getting more data processed at faster rate in the CPU. Finaly, hyperthreading, which was on the older Pentium 4 HT processors, is coming back with some enhancements. It can now double the amount of data to process in the clock cycle in one core. For those who don't know/remember how it work, we can say that it try to fill blank and thus unused quarter of CPU clock by filling them with an other thread.

Power to fill
While all those technologies get super processing power to the CPU they made it harder to fill with data. That's where the new Integrated memory controller and Advanced Smart Cache technology come in place. Those two little guy help at fetching data in the processor up to three times faster than on the previous processors by using a faster connection to memory and three channel instead of two and the second one make data closer to every core of every processors thus nearly dividing by four the latency needed to check if a core is working on the same data as an other. Those little thing contribute on the 45% performance improvement over the older Penryn generation.

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