1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)proc_compare.c 8.2 (Berkeley) 9/23/93 34 * 35 * $DragonFly: src/usr.bin/w/proc_compare.c,v 1.8 2007/02/18 16:12:43 corecode Exp $ 36 */ 37 38 #include <sys/param.h> 39 #include <sys/time.h> 40 #include <sys/user.h> 41 42 #include "extern.h" 43 44 /* 45 * Returns 1 if p2 is "better" than p1 46 * 47 * The algorithm for picking the "interesting" process is thus: 48 * 49 * 1) Only foreground processes are eligible - implied. 50 * 2) Runnable processes are favored over anything else. The runner 51 * with the highest cpu utilization is picked (p_estcpu). Ties are 52 * broken by picking the highest pid. 53 * 3) The sleeper with the shortest sleep time is next. With ties, 54 * we pick out just "short-term" sleepers (LWP_SINTR == 0). 55 * 4) Further ties are broken by picking the highest pid. 56 * 57 * If you change this, be sure to consider making the change in the kernel 58 * too (^T in kern/tty.c). 59 * 60 * TODO - consider whether pctcpu should be used. 61 */ 62 63 #define ISRUN(p) ((p)->kp_lwp.kl_stat == LSRUN) 64 #define TESTAB(a, b) ((a)<<1 | (b)) 65 #define ONLYA 2 66 #define ONLYB 1 67 #define BOTH 3 68 69 int 70 proc_compare(struct kinfo_proc *p1, struct kinfo_proc *p2) 71 { 72 73 if (p1 == NULL) 74 return (1); 75 /* 76 * see if at least one of them is runnable 77 */ 78 switch (TESTAB(ISRUN(p1), ISRUN(p2))) { 79 case ONLYA: 80 return (0); 81 case ONLYB: 82 return (1); 83 case BOTH: 84 /* 85 * tie - favor one with highest recent cpu utilization 86 */ 87 if (p2->kp_lwp.kl_estcpu > p1->kp_lwp.kl_estcpu) 88 return (1); 89 if (p1->kp_lwp.kl_estcpu > p2->kp_lwp.kl_estcpu) 90 return (0); 91 return (p2->kp_pid > p1->kp_pid); /* tie - return highest pid */ 92 } 93 /* 94 * weed out zombies 95 */ 96 switch (TESTAB(p1->kp_flags & P_ZOMBIE, p2->kp_flags & P_ZOMBIE)) { 97 case ONLYA: 98 return (1); 99 case ONLYB: 100 return (0); 101 case BOTH: 102 return (p2->kp_pid > p1->kp_pid); /* tie - return highest pid */ 103 } 104 /* 105 * pick the one with the smallest sleep time 106 */ 107 if (p2->kp_lwp.kl_slptime > p1->kp_lwp.kl_slptime) 108 return (0); 109 if (p1->kp_lwp.kl_slptime > p2->kp_lwp.kl_slptime) 110 return (1); 111 /* 112 * favor one sleeping in a non-interruptible sleep 113 */ 114 if (p1->kp_lwp.kl_flags & LWP_SINTR && (p2->kp_lwp.kl_flags & LWP_SINTR) == 0) 115 return (1); 116 if (p2->kp_lwp.kl_flags & LWP_SINTR && (p1->kp_lwp.kl_flags & LWP_SINTR) == 0) 117 return (0); 118 return (p2->kp_pid > p1->kp_pid); /* tie - return highest pid */ 119 } 120