An Introduction to Timekeeping in Linux VMs

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Keeping time in Linux is not simple, and virtualization adds additional challenges and opportunities. In this article, I’ll review KVM, Xen, and Hyper-V related time-keeping techniques and the corresponding parts of the Linux kernel.

Timekeeping is the process or activity of recording how long something takes. We need “instruments” to measure time. The Linux kernel has several abstractions to represent such devices:

  • Clocksource is a device that can give a timestamp whenever you need it. In other words, Clocksource is any ticking counter that allows you to get its value.

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