Do some fairly major include file cleanups to further separate kernelland
[dragonfly.git] / usr.bin / w / proc_compare.c
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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.
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32 *
33 * @(#)proc_compare.c 8.2 (Berkeley) 9/23/93
1d1731fa 34 *
05220613 35 * $DragonFly: src/usr.bin/w/proc_compare.c,v 1.4 2003/11/21 22:46:15 dillon Exp $
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36 */
37
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38#include <sys/param.h>
39#include <sys/time.h>
05220613 40#include <sys/user.h>
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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 (P_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)->p_stat == SRUN) || ((p)->p_stat == SIDL))
64#define TESTAB(a, b) ((a)<<1 | (b))
65#define ONLYA 2
66#define ONLYB 1
67#define BOTH 3
68
69int
1d1731fa 70proc_compare(register struct proc *p1, register struct proc *p2)
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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->p_estcpu > p1->p_estcpu)
88 return (1);
89 if (p1->p_estcpu > p2->p_estcpu)
90 return (0);
91 return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
92 }
93 /*
94 * weed out zombies
95 */
96 switch (TESTAB(p1->p_stat == SZOMB, p2->p_stat == SZOMB)) {
97 case ONLYA:
98 return (1);
99 case ONLYB:
100 return (0);
101 case BOTH:
102 return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
103 }
104 /*
105 * pick the one with the smallest sleep time
106 */
107 if (p2->p_slptime > p1->p_slptime)
108 return (0);
109 if (p1->p_slptime > p2->p_slptime)
110 return (1);
111 /*
112 * favor one sleeping in a non-interruptible sleep
113 */
114 if (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
115 return (1);
116 if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
117 return (0);
118 return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
119}