Over the last 5 years, high performance microprocessors have changed dramatically. One of the most significant influences is the increasing level of integration that is enabled by Moore’s Law. In the context of semiconductors, integration is an ever-present fact of life, reducing system power consumption and cost and increasing performance. The latest incarnation of this trend is the System-on-a-Chip (SoC) philosophy and design approach. SoCs have been the preferred solution for extremely low power systems, such as 1W mobile phone chips. However, high performance microprocessors span a much wider design space, from 15W notebook chips to 150W server sockets and the adoption of SoCs has been slower because of the more diverse market.
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The most in-depth overview of Haswell I've read.
A definite "must read" for everyone interested in CPU architecture.