Making the best use of available memory is one of the biggest challenges for any operating system. Throwing virtualization into the mix adds both new challenges (balancing memory use between guests, for example) and opportunities (sharing pages between guests). Developers have responded with technologies like hot-plug memory and KSM, but nobody seems to think that the problem is fully solved. "Transcendent memory" is a new idea which has recently been proposed as a way of optimizing a system's use of memory; click below (subscribers only) for a look at transcendent memory from this week's Kernel page.

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