libc/gen/clock.c

1.10  christos /*	$NetBSD: clock.c,v 1.10 2009/01/11 02:46:27 christos Exp $	*/
 1.5       cgd
 1.1       cgd /*
 1.5       cgd  * Copyright (c) 1989, 1993
 1.5       cgd  *	The Regents of the University of California.  All rights reserved.
 1.1       cgd  *
 1.1       cgd  * Redistribution and use in source and binary forms, with or without
 1.1       cgd  * modification, are permitted provided that the following conditions
 1.1       cgd  * are met:
 1.1       cgd  * 1. Redistributions of source code must retain the above copyright
 1.1       cgd  *    notice, this list of conditions and the following disclaimer.
 1.1       cgd  * 2. Redistributions in binary form must reproduce the above copyright
 1.1       cgd  *    notice, this list of conditions and the following disclaimer in the
 1.1       cgd  *    documentation and/or other materials provided with the distribution.
 1.8       agc  * 3. Neither the name of the University nor the names of its contributors
 1.1       cgd  *    may be used to endorse or promote products derived from this software
 1.1       cgd  *    without specific prior written permission.
 1.1       cgd  *
 1.1       cgd  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 1.1       cgd  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 1.1       cgd  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 1.1       cgd  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 1.1       cgd  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 1.1       cgd  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 1.1       cgd  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 1.1       cgd  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 1.1       cgd  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 1.1       cgd  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 1.1       cgd  * SUCH DAMAGE.
 1.1       cgd  */
 1.1       cgd
 1.6  christos #include <sys/cdefs.h>
 1.1       cgd #if defined(LIBC_SCCS) && !defined(lint)
 1.5       cgd #if 0
 1.5       cgd static char sccsid[] = "@(#)clock.c	8.1 (Berkeley) 6/4/93";
 1.5       cgd #else
1.10  christos __RCSID("$NetBSD: clock.c,v 1.10 2009/01/11 02:46:27 christos Exp $");
 1.5       cgd #endif
 1.1       cgd #endif /* LIBC_SCCS and not lint */
 1.1       cgd
 1.1       cgd #include <sys/param.h>
 1.1       cgd #include <sys/time.h>
 1.1       cgd #include <sys/resource.h>
 1.7    kleink
 1.7    kleink #include <time.h>
 1.1       cgd
 1.1       cgd /*
 1.9       dsl  * This code is all rather silly because the kernel counts actual
 1.9       dsl  * execution time (to usec accuracy) then splits it into user, system and
 1.9       dsl  * interrupt based on when clock ticks happen.  getrusage apportions the
 1.9       dsl  * time based on the number of ticks, and here we are trying to generate
 1.9       dsl  * a number which was, traditionally, the number of ticks!
 1.9       dsl  *
 1.9       dsl  * Due to the way the time is apportioned, this code (and indeed getrusage
 1.9       dsl  * itself) are not guaranteed monotonic.
 1.1       cgd  */
 1.1       cgd
 1.1       cgd clock_t
1.10  christos clock(void)
 1.1       cgd {
 1.1       cgd 	struct rusage ru;
 1.9       dsl 	clock_t hz = CLOCKS_PER_SEC;
 1.1       cgd
 1.1       cgd 	if (getrusage(RUSAGE_SELF, &ru))
 1.1       cgd 		return ((clock_t) -1);
1.10  christos 	return (clock_t)((ru.ru_utime.tv_sec + ru.ru_stime.tv_sec) * hz +
1.10  christos 	    (ru.ru_utime.tv_usec + ru.ru_stime.tv_usec + 50)
1.10  christos 	    / 100 * hz / 10000);
 1.1       cgd }