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Full Discussion: semaphore access speed
Top Forums Programming semaphore access speed Post 302238331 by jim mcnamara on Friday 19th of September 2008 03:27:02 PM
Old 09-19-2008
PS call utimes(struct tms *) to actual times, plus granularity is CLK_TCK, usually way better than time().

gettimeofday can be used to get wall time even more accurately as well. utimes() returns clock_t wall time.
 

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TIMES(3)						   BSD Library Functions Manual 						  TIMES(3)

NAME
times -- process times LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/times.h> clock_t times(struct tms *buffer); DESCRIPTION
This interface is obsoleted by getrusage(2) and gettimeofday(2). The times() function returns the value of time in CLK_TCK's of a second since 0 hours, 0 minutes, 0 seconds, January 1, 1970, Coordinated Universal Time. It also fills in the structure pointed to by buffer with time-accounting information. The tms structure is defined as follows: struct tms { clock_t tms_utime; clock_t tms_stime; clock_t tms_cutime; clock_t tms_cstime; }; The elements of this structure are defined as follows: tms_utime The CPU time charged for the execution of user instructions. tms_stime The CPU time charged for execution by the system on behalf of the process. tms_cutime The sum of the tms_utimes and tms_cutimes of the child processes. tms_cstime The sum of the tms_stimes and tms_cstimes of the child processes. All times are in CLK_TCK's of a second. The times of a terminated child process are included in the tms_cutime and tms_cstime elements of the parent when one of the wait(2) func- tions returns the process ID of the terminated child to the parent. If an error occurs, times() returns the value ((clock_t)-1), and sets errno to indicate the error. ERRORS
The times() function may fail and set the global variable errno for any of the errors specified for the library routines getrusage(2) and gettimeofday(2). SEE ALSO
time(1), getrusage(2), gettimeofday(2), wait(2), clocks(7) STANDARDS
The times() function conforms to IEEE Std 1003.1-1988 (``POSIX.1''). BSD
June 4, 1993 BSD
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