> The way Linux does that is to use the time-stamping counter of the > processor (the rdtsc instructions), which (originally) counts one unit > per CPU clock. I believe current processors use slightly different > countings (e.g. through the APIC), but still: you get a resolution > within the clock frequency of the CPU quartz.
Linux has an internal clocksource API supporting different hardwares: PIT (Intel 8253 chipset): configurable frequency between 8.2 Hz and 1.2 MHz PMTMR (power management timer): ACPI clock with a frequency of 3.5 MHz TSC (Time Stamp Counter): frequency of your CPU HPET (High Precision Event Timer): frequency of at least 10 MHz (14.3 MHz on my computer) Linux has an algorithm to choose the best clock depend on its performance and accurary. Most clocks have a frequency higher than 1 MHz and so a resolution smaller than 1 us, even if the clock is not really accurate. I suppose that you can plug specialized hardward like an atomic clocks, or a GPS receiver, for a better accurary. Victor _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
