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. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#if 0
31#ifndef lint
32static char sccsid[] = "@(#)proc_compare.c	8.2 (Berkeley) 9/23/93";
33#endif /* not lint */
34#endif
35
36#include <sys/cdefs.h>
37#ifndef __APPLE__
38__FBSDID("$FreeBSD: src/usr.bin/w/proc_compare.c,v 1.9 2004/04/14 09:34:17 bde Exp $");
39#endif
40
41#include <sys/param.h>
42#ifdef __APPLE__
43#include <sys/time.h>
44#endif
45#include <sys/proc.h>
46#include <sys/time.h>
47#include <sys/user.h>
48
49#include "extern.h"
50
51/*
52 * Returns 1 if p2 is "better" than p1
53 *
54 * The algorithm for picking the "interesting" process is thus:
55 *
56 *	1) Only foreground processes are eligible - implied.
57 *	2) Runnable processes are favored over anything else.  The runner
58 *	   with the highest cpu utilization is picked (p_estcpu).  Ties are
59 *	   broken by picking the highest pid.
60 *	3) The sleeper with the shortest sleep time is next.  With ties,
61 *	   we pick out just "short-term" sleepers (TDF_SINTR == 0).
62 *	4) Further ties are broken by picking the highest pid.
63 *
64 * If you change this, be sure to consider making the change in the kernel
65 * too (^T in kern/tty.c).
66 *
67 * TODO - consider whether pctcpu should be used.
68 */
69
70#if !HAVE_KVM
71#define ki_estcpu	p_estcpu
72#define ki_pid		p_pid
73#define ki_slptime	p_slptime
74#define ki_stat		p_stat
75#define ki_tdflags	p_tdflags
76#endif
77
78#define ISRUN(p)	(((p)->ki_stat == SRUN) || ((p)->ki_stat == SIDL))
79#define TESTAB(a, b)    ((a)<<1 | (b))
80#define ONLYA   2
81#define ONLYB   1
82#define BOTH    3
83
84#if HAVE_KVM
85int
86proc_compare(struct kinfo_proc *p1, struct kinfo_proc *p2)
87{
88#else
89int
90proc_compare(struct kinfo_proc *arg1, struct kinfo_proc *arg2)
91{
92	struct extern_proc* p1 = &arg1->kp_proc;
93	struct extern_proc* p2 = &arg2->kp_proc;
94#endif
95
96	if (p1 == NULL)
97		return (1);
98	/*
99	 * see if at least one of them is runnable
100	 */
101	switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
102	case ONLYA:
103		return (0);
104	case ONLYB:
105		return (1);
106	case BOTH:
107		/*
108		 * tie - favor one with highest recent cpu utilization
109		 */
110		if (p2->ki_estcpu > p1->ki_estcpu)
111			return (1);
112		if (p1->ki_estcpu > p2->ki_estcpu)
113			return (0);
114		return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */
115	}
116	/*
117 	 * weed out zombies
118	 */
119	switch (TESTAB(p1->ki_stat == SZOMB, p2->ki_stat == SZOMB)) {
120	case ONLYA:
121		return (1);
122	case ONLYB:
123		return (0);
124	case BOTH:
125		return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */
126	}
127	/*
128	 * pick the one with the smallest sleep time
129	 */
130	if (p2->ki_slptime > p1->ki_slptime)
131		return (0);
132	if (p1->ki_slptime > p2->ki_slptime)
133		return (1);
134#ifndef __APPLE__
135	/*
136	 * favor one sleeping in a non-interruptible sleep
137	 */
138	if (p1->ki_tdflags & TDF_SINTR && (p2->ki_tdflags & TDF_SINTR) == 0)
139		return (1);
140	if (p2->ki_tdflags & TDF_SINTR && (p1->ki_tdflags & TDF_SINTR) == 0)
141		return (0);
142#endif
143	return (p2->ki_pid > p1->ki_pid);	/* tie - return highest pid */
144}
145