1 /* $NetBSD: clock.c,v 1.10 2009/01/11 02:46:27 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 #if 0 35 static char sccsid[] = "@(#)clock.c 8.1 (Berkeley) 6/4/93"; 36 #else 37 __RCSID("$NetBSD: clock.c,v 1.10 2009/01/11 02:46:27 christos Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <sys/param.h> 42 #include <sys/time.h> 43 #include <sys/resource.h> 44 45 #include <time.h> 46 47 /* 48 * This code is all rather silly because the kernel counts actual 49 * execution time (to usec accuracy) then splits it into user, system and 50 * interrupt based on when clock ticks happen. getrusage apportions the 51 * time based on the number of ticks, and here we are trying to generate 52 * a number which was, traditionally, the number of ticks! 53 * 54 * Due to the way the time is apportioned, this code (and indeed getrusage 55 * itself) are not guaranteed monotonic. 56 */ 57 58 clock_t 59 clock(void) 60 { 61 struct rusage ru; 62 clock_t hz = CLOCKS_PER_SEC; 63 64 if (getrusage(RUSAGE_SELF, &ru)) 65 return ((clock_t) -1); 66 return (clock_t)((ru.ru_utime.tv_sec + ru.ru_stime.tv_sec) * hz + 67 (ru.ru_utime.tv_usec + ru.ru_stime.tv_usec + 50) 68 / 100 * hz / 10000); 69 } 70