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On 16/08/2011 12.17, Lorenzo Donati wrote:
To be clearer: I'd like to know (whether or not an OS chooses to provide an high resolution sleep function) if the modern PC hardware is capable of providing such a timing resolution to the upper sw layer by default (using some standard BIOS call or standard I/O port or whatever), or if it depends on some peculiar hw characteristic such as CPU setup, chipset or similar things.
As far as I know, most (all?) modern CPUs have a high-resolution timer in the nanosecond range; I don't think there's a portable call to access it across different OSs, though (I may be wrong).
Of course it would be unwise to implement a true 'sleep' function with such a short time duration, because of complications such as interference with the task scheduler and unpredictable interrupt latency (assuming interrupt could be used; I don't think so in the general case); it would have to be a busy loop, with all that this implies, or if possible a periodic check while doing some other processing.
-- Enrico