HPL_ptimer_cputime Return the CPU time.
returns the cpu time. If HPL_USE_CLOCK is defined,
the clock() function is used to return an approximation of processor
time used by the program. The value returned is the CPU time used so
far as a clock_t; to get the number of seconds used, the result is
divided by CLOCKS_PER_SEC. This function is part of the ANSI/ISO C
standard library. If HPL_USE_TIMES is defined, the times() function
is used instead. This function returns the current process times.
times() returns the number of clock ticks that have elapsed since the
system has been up. Otherwise and by default, the standard library
function getrusage() is used.