I updated my PEP 564 to add time.process_time_ns(): https://github.com/python/peps/blob/master/pep-0564.rst
The HTML version should be updated shortly: https://www.python.org/dev/peps/pep-0564/ I better explained why some functions got a new nanosecond variant, whereas others don't. The rationale is the precision loss affecting only a few functions in practice. I completed the "Annex: Clocks Resolution in Python" with more numbers, again, to explain why some functions don't need a nanosecond variant. Thanks Antoine, the PEP now looks better to me :-) Victor 2017-10-18 0:05 GMT+02:00 Victor Stinner <victor.stin...@gmail.com>: > Antoine Pitrou: >> Why not ``time.process_time_ns()``? > > I measured the minimum delta between two clock reads, ignoring zeros. > I tested time.process_time(), os.times(), resource.getrusage(), and > their nanosecond variants (with my WIP implementation of the PEP 564). > > Linux: > > * process_time_ns(): 1 ns > * process_time(): 2 ns > * resource.getrusage(): 1 us > ru_usage structure uses timeval, so it makes sense > * clock(): 1 us > CLOCKS_PER_SECOND = 1,000,000 => res = 1 us > * times_ns().elapsed, times().elapsed: 10 ms > os.sysconf("SC_CLK_TCK") == HZ = 100 => res = 10 ms > * times_ns().user, times().user: 10 ms > os.sysconf("SC_CLK_TCK") == HZ = 100 => res = 10 ms > > Windows: > > * process_time(), process_time_ns(): 15.6 ms > * os.times().user, os.times_ns().user: 15.6 ms > > Note: I didn't test os.wait3() and os.wait4(), but they also use the > ru_usage structure and so probably also have a resolution of 1 us. > > It looks like *currently*, only time.process_time() has a resolution > in nanoseconds (smaller than 1 us). I propose to only add > time.process_time_ns(), as you proposed. > > We might add nanosecond variant for the other functions once operating > systems will add new functions with better resolution. > > Victor _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
