MojoKid writes "big.LITTLE is ARM's solution to a particularly nasty problem: smaller and smaller process nodes no longer deliver the kind of overall power consumption improvements they did years ago. Before 90nm technology, semiconductor firms could count on new chips being smaller, faster, and drawing less power at a given frequency. Eventually, that stopped being true. Tighter process geometries still pack more transistors per square millimeter, but the improvements to power consumption and maximum frequency have been falling with each smaller node. Rising defect densities have created a situation where — for the first time ever — 20nm wafers won't be cheaper than the 28nm processors they're supposed to replace. This is a critical problem for the mobile market, where low power consumption is absolutely vital. big.LITTLE is ARM's answer to this problem. The strategy requires manufacturers to implement two sets of cores — the Cortex-A7 and Cortex-A15 are the current match-up. The idea is for the little cores to handle the bulk of the device's work, with the big cores used for occasional heavy lifting. ARM's argument is that this approach is superior to dynamic voltage and frequency scaling (DVFS) because it's impossible for a single CPU architecture to retain a linear performance/power curve across its entire frequency range. This is the same argument Nvidia made when it built the Companion Core in Tegra 3."
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