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I am unaware of any hardware source for a high resolution time other than this CPU feature. I'd be curious if somebody knows of some alternative.

On windows, Time::HiRes uses QueryPerformanceCounter + GetSystemTimeAsFileTime. The former is underlain by the most accurate hardware timer available on the PC. This varies (increasing in accuracy) as the age of the hardware lessens.

Since circa 2005, all modern PCs have had a High Precision Event Time available as a part of the hardware. This is unaffected by clock speed energy management and lies outside of the number of cores or hyper-threads.

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In reply to Re^2: negative elapsed time? by BrowserUk
in thread negative elapsed time? by saneel

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