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 34 #ifndef lint 35 #if 0 36 static char sccsid[] = "@(#)proc_compare.c 8.2 (Berkeley) 9/23/93"; 37 #endif 38 static const char rcsid[] = 39 "$FreeBSD$"; 40 #endif /* not lint */ 41 42 #include <sys/param.h> 43 #include <sys/time.h> 44 #include <sys/user.h> 45 46 #include "extern.h" 47 48 /* 49 * Returns 1 if p2 is "better" than p1 50 * 51 * The algorithm for picking the "interesting" process is thus: 52 * 53 * 1) Only foreground processes are eligible - implied. 54 * 2) Runnable processes are favored over anything else. The runner 55 * with the highest cpu utilization is picked (p_estcpu). Ties are 56 * broken by picking the highest pid. 57 * 3) The sleeper with the shortest sleep time is next. With ties, 58 * we pick out just "short-term" sleepers (PS_SINTR == 0). 59 * 4) Further ties are broken by picking the highest pid. 60 * 61 * If you change this, be sure to consider making the change in the kernel 62 * too (^T in kern/tty.c). 63 * 64 * TODO - consider whether pctcpu should be used. 65 */ 66 67 #define ISRUN(p) (((p)->ki_stat == SRUN) || ((p)->ki_stat == SIDL)) 68 #define TESTAB(a, b) ((a)<<1 | (b)) 69 #define ONLYA 2 70 #define ONLYB 1 71 #define BOTH 3 72 73 int 74 proc_compare(p1, p2) 75 struct kinfo_proc *p1, *p2; 76 { 77 78 if (p1 == NULL) 79 return (1); 80 /* 81 * see if at least one of them is runnable 82 */ 83 switch (TESTAB(ISRUN(p1), ISRUN(p2))) { 84 case ONLYA: 85 return (0); 86 case ONLYB: 87 return (1); 88 case BOTH: 89 /* 90 * tie - favor one with highest recent cpu utilization 91 */ 92 if (p2->ki_estcpu > p1->ki_estcpu) 93 return (1); 94 if (p1->ki_estcpu > p2->ki_estcpu) 95 return (0); 96 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */ 97 } 98 /* 99 * weed out zombies 100 */ 101 switch (TESTAB(p1->ki_stat == SZOMB, p2->ki_stat == SZOMB)) { 102 case ONLYA: 103 return (1); 104 case ONLYB: 105 return (0); 106 case BOTH: 107 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */ 108 } 109 /* 110 * pick the one with the smallest sleep time 111 */ 112 if (p2->ki_slptime > p1->ki_slptime) 113 return (0); 114 if (p1->ki_slptime > p2->ki_slptime) 115 return (1); 116 /* 117 * favor one sleeping in a non-interruptible sleep 118 */ 119 if (p1->ki_tdflags & TDF_SINTR && (p2->ki_tdflags & TDF_SINTR) == 0) 120 return (1); 121 if (p2->ki_tdflags & TDF_SINTR && (p1->ki_tdflags & TDF_SINTR) == 0) 122 return (0); 123 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */ 124 } 125