projects / apple / shell_cmds.git / blame
| Commit | Line | Data |
|---|---|---|
| 44bd5ea7 A |
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 | #include <sys/cdefs.h> | |
| 9bafe280 | 35 | |
| 44bd5ea7 | 36 | #ifndef lint |
| 9bafe280 | 37 | static const char sccsid[] = "@(#)proc_compare.c 8.2 (Berkeley) 9/23/93"; |
| 44bd5ea7 | 38 | #endif |
| 44bd5ea7 A |
39 | |
| 40 | #include <sys/param.h> | |
| 41 | #include <sys/time.h> | |
| 9bafe280 | 42 | #include <sys/user.h> |
| 44bd5ea7 A |
43 | |
| 44 | #include "extern.h" | |
| 45 | ||
| 46 | /* | |
| 47 | * Returns 1 if p2 is "better" than p1 | |
| 48 | * | |
| 49 | * The algorithm for picking the "interesting" process is thus: | |
| 50 | * | |
| 51 | * 1) Only foreground processes are eligible - implied. | |
| 52 | * 2) Runnable processes are favored over anything else. The runner | |
| 53 | * with the highest cpu utilization is picked (p_estcpu). Ties are | |
| 54 | * broken by picking the highest pid. | |
| 55 | * 3) The sleeper with the shortest sleep time is next. With ties, | |
| 9bafe280 | 56 | * we pick out just "short-term" sleepers (PS_SINTR == 0). |
| 44bd5ea7 A |
57 | * 4) Further ties are broken by picking the highest pid. |
| 58 | * | |
| 59 | * If you change this, be sure to consider making the change in the kernel | |
| 60 | * too (^T in kern/tty.c). | |
| 61 | * | |
| 62 | * TODO - consider whether pctcpu should be used. | |
| 63 | */ | |
| 64 | ||
| 9bafe280 A |
65 | #include <sys/cdefs.h> |
| 66 | ||
| 67 | ||
| 68 | #define ISRUN(p) (((p)->p_stat == SRUN) || ((p)->p_stat == SIDL)) | |
| 44bd5ea7 A |
69 | #define TESTAB(a, b) ((a)<<1 | (b)) |
| 70 | #define ONLYA 2 | |
| 71 | #define ONLYB 1 | |
| 72 | #define BOTH 3 | |
| 73 | ||
| 74 | int | |
| 75 | proc_compare(p1, p2) | |
| 9bafe280 | 76 | struct extern_proc *p1, *p2; |
| 44bd5ea7 A |
77 | { |
| 78 | ||
| 79 | if (p1 == NULL) | |
| 80 | return (1); | |
| 81 | /* | |
| 82 | * see if at least one of them is runnable | |
| 83 | */ | |
| 84 | switch (TESTAB(ISRUN(p1), ISRUN(p2))) { | |
| 85 | case ONLYA: | |
| 86 | return (0); | |
| 87 | case ONLYB: | |
| 88 | return (1); | |
| 89 | case BOTH: | |
| 90 | /* | |
| 91 | * tie - favor one with highest recent cpu utilization | |
| 92 | */ | |
| 93 | if (p2->p_estcpu > p1->p_estcpu) | |
| 94 | return (1); | |
| 95 | if (p1->p_estcpu > p2->p_estcpu) | |
| 96 | return (0); | |
| 97 | return (p2->p_pid > p1->p_pid); /* tie - return highest pid */ | |
| 98 | } | |
| 99 | /* | |
| 100 | * weed out zombies | |
| 101 | */ | |
| 102 | switch (TESTAB(p1->p_stat == SZOMB, p2->p_stat == SZOMB)) { | |
| 103 | case ONLYA: | |
| 104 | return (1); | |
| 105 | case ONLYB: | |
| 106 | return (0); | |
| 107 | case BOTH: | |
| 108 | return (p2->p_pid > p1->p_pid); /* tie - return highest pid */ | |
| 109 | } | |
| 110 | /* | |
| 111 | * pick the one with the smallest sleep time | |
| 112 | */ | |
| 113 | if (p2->p_slptime > p1->p_slptime) | |
| 114 | return (0); | |
| 115 | if (p1->p_slptime > p2->p_slptime) | |
| 116 | return (1); | |
| 9bafe280 | 117 | return (p2->p_pid > p1->p_pid); /* tie - return highest pid */ |
| 44bd5ea7 | 118 | } |