getrusage vs clock
Paul.Zimmermann at inria.fr
Thu Jan 21 13:02:39 UTC 2016
> since version 2.18 of the glibc, the clock() function is much more precise.
> For example on my machine it has a resolution of 1 micro-seconds whereas
> getrusage() has a resolution of 4ms only, as demonstrated by the program
> I believe we already use clock_gettime(2) directly on GNU/Linux, which
> is the underlying syscall that clock(3) uses in newer GNU libc versions.
> Does that not happen in your tests?
I don't know how to check which function is used. With gmp-6.1.0 on my
workstation I get:
zimmerma at tomate:/tmp/gmp-6.1.0/tune$ ./speed
CPU cycle counter, supplemented by microsecond getrusage()
Gnuplot home page http://www.gnuplot.info/
Quickplot home page http://quickplot.sourceforge.net/
which lets me think that getrusage() is still used.
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