1/* $NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $ */ 2 3/*- 4 * Copyright (c) 1990, 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#ifndef _STANDALONE 32# ifndef _KERNEL 33 34# if HAVE_NBTOOL_CONFIG_H 35# include "nbtool_config.h" 36# endif 37 38# include <sys/cdefs.h> 39# if defined(LIBC_SCCS) && !defined(lint) 40__RCSID("$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $"); 41# endif 42 43# include <sys/types.h> 44# include <sys/inttypes.h> 45# include <sys/sysctl.h> 46# include <stdio.h> 47# include <util.h> 48# include <errno.h> 49# define PROC struct kinfo_proc2 50# define LWP struct kinfo_lwp 51# define P_RTIME_SEC p_rtime_sec 52# define P_RTIME_USEC p_rtime_usec 53# else 54# include <sys/cdefs.h> 55__KERNEL_RCSID(0, "$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $"); 56# include <sys/param.h> 57# include <sys/inttypes.h> 58# include <sys/systm.h> 59# include <sys/proc.h> 60# include <sys/lwp.h> 61# include <lib/libkern/libkern.h> 62# define PROC struct proc 63# define LWP struct lwp 64# define P_RTIME_SEC p_rtime.sec 65# define P_RTIME_USEC p_rtime.frac 66# endif 67/* 68 * Returns 1 if p2 is "better" than p1 69 * 70 * The algorithm for picking the "interesting" process is thus: 71 * 72 * 1) Only foreground processes are eligible - implied. 73 * 2) Runnable processes are favored over anything else. The runner 74 * with the highest CPU utilization is picked (l_pctcpu). Ties are 75 * broken by picking the highest pid. 76 * 3) The sleeper with the shortest sleep time is next. With ties, 77 * we pick out just "short-term" sleepers (P_SINTR == 0). 78 * 4) Further ties are broken by picking the one started last. 79 * 5) Finally the one with the biggest pid wins, but that is nonsense 80 * because of pid randomization. 81 */ 82#define ISRUN(p) ((p)->p_nrlwps > 0) 83#define TESTAB(a, b) (((a) << 1) | (b)) 84#define ONLYA 2 85#define ONLYB 1 86#define BOTH 3 87 88int 89proc_compare(const PROC *p1, const LWP *l1, const PROC *p2, const LWP *l2) 90{ 91 /* 92 * see if at least one of them is runnable 93 */ 94 switch (TESTAB(ISRUN(p1), ISRUN(p2))) { 95 case ONLYA: 96 return 0; 97 case ONLYB: 98 return 1; 99 case BOTH: 100 /* 101 * tie - favor one with highest recent CPU utilization 102 */ 103 if (l2->l_pctcpu > l1->l_pctcpu) 104 return 1; 105 goto out; 106 } 107 /* 108 * weed out zombies 109 */ 110 switch (TESTAB(P_ZOMBIE(p1), P_ZOMBIE(p2))) { 111 case ONLYA: 112 return 1; 113 case ONLYB: 114 return 0; 115 case BOTH: 116 goto out; 117 } 118 /* 119 * pick the one with the smallest sleep time 120 */ 121 if (l1->l_slptime < l2->l_slptime) 122 return 0; 123 if (l2->l_slptime < l1->l_slptime) 124 return 1; 125 126 /* 127 * favor one sleeping in a non-interruptible sleep 128 */ 129 if ((l1->l_flag & LW_SINTR) && (l2->l_flag & LW_SINTR) == 0) 130 return 0; 131 if ((l2->l_flag & LW_SINTR) && (l1->l_flag & LW_SINTR) == 0) 132 return 1; 133out: 134 /* tie, return the one with the smallest realtime */ 135 if (p1->P_RTIME_SEC < p2->P_RTIME_SEC) 136 return 0; 137 if (p2->P_RTIME_SEC < p1->P_RTIME_SEC) 138 return 1; 139 if (p1->P_RTIME_USEC < p2->P_RTIME_USEC) 140 return 0; 141 if (p2->P_RTIME_USEC < p1->P_RTIME_USEC) 142 return 1; 143 144 return p2->p_pid > p1->p_pid; /* Nonsense */ 145} 146#endif /* STANDALONE */ 147