1 /* $NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31 #ifndef _STANDALONE
32 # ifndef _KERNEL
33
34 # if HAVE_NBTOOL_CONFIG_H
35 # include "nbtool_config.h"
36 # endif
37
38 # include <sys/cdefs.h>
39 # if defined(LIBC_SCCS) && !defined(lint)
40 __RCSID("$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $");
41 # endif
42
43 # include <sys/types.h>
44 # include <sys/inttypes.h>
45 # include <sys/sysctl.h>
46 # include <stdio.h>
47 # include <util.h>
48 # include <errno.h>
49 # define PROC struct kinfo_proc2
50 # define LWP struct kinfo_lwp
51 # define P_RTIME_SEC p_rtime_sec
52 # define P_RTIME_USEC p_rtime_usec
53 # else
54 # include <sys/cdefs.h>
55 __KERNEL_RCSID(0, "$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $");
56 # include <sys/param.h>
57 # include <sys/inttypes.h>
58 # include <sys/systm.h>
59 # include <sys/proc.h>
60 # include <sys/lwp.h>
61 # include <lib/libkern/libkern.h>
62 # define PROC struct proc
63 # define LWP struct lwp
64 # define P_RTIME_SEC p_rtime.sec
65 # define P_RTIME_USEC p_rtime.frac
66 # endif
67 /*
68 * Returns 1 if p2 is "better" than p1
69 *
70 * The algorithm for picking the "interesting" process is thus:
71 *
72 * 1) Only foreground processes are eligible - implied.
73 * 2) Runnable processes are favored over anything else. The runner
74 * with the highest CPU utilization is picked (l_pctcpu). Ties are
75 * broken by picking the highest pid.
76 * 3) The sleeper with the shortest sleep time is next. With ties,
77 * we pick out just "short-term" sleepers (P_SINTR == 0).
78 * 4) Further ties are broken by picking the one started last.
79 * 5) Finally the one with the biggest pid wins, but that is nonsense
80 * because of pid randomization.
81 */
82 #define ISRUN(p) ((p)->p_nrlwps > 0)
83 #define TESTAB(a, b) (((a) << 1) | (b))
84 #define ONLYA 2
85 #define ONLYB 1
86 #define BOTH 3
87
88 int
proc_compare(const PROC * p1,const LWP * l1,const PROC * p2,const LWP * l2)89 proc_compare(const PROC *p1, const LWP *l1, const PROC *p2, const LWP *l2)
90 {
91 /*
92 * see if at least one of them is runnable
93 */
94 switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
95 case ONLYA:
96 return 0;
97 case ONLYB:
98 return 1;
99 case BOTH:
100 /*
101 * tie - favor one with highest recent CPU utilization
102 */
103 if (l2->l_pctcpu > l1->l_pctcpu)
104 return 1;
105 goto out;
106 }
107 /*
108 * weed out zombies
109 */
110 switch (TESTAB(P_ZOMBIE(p1), P_ZOMBIE(p2))) {
111 case ONLYA:
112 return 1;
113 case ONLYB:
114 return 0;
115 case BOTH:
116 goto out;
117 }
118 /*
119 * pick the one with the smallest sleep time
120 */
121 if (l1->l_slptime < l2->l_slptime)
122 return 0;
123 if (l2->l_slptime < l1->l_slptime)
124 return 1;
125
126 /*
127 * favor one sleeping in a non-interruptible sleep
128 */
129 if ((l1->l_flag & LW_SINTR) && (l2->l_flag & LW_SINTR) == 0)
130 return 0;
131 if ((l2->l_flag & LW_SINTR) && (l1->l_flag & LW_SINTR) == 0)
132 return 1;
133 out:
134 /* tie, return the one with the smallest realtime */
135 if (p1->P_RTIME_SEC < p2->P_RTIME_SEC)
136 return 0;
137 if (p2->P_RTIME_SEC < p1->P_RTIME_SEC)
138 return 1;
139 if (p1->P_RTIME_USEC < p2->P_RTIME_USEC)
140 return 0;
141 if (p2->P_RTIME_USEC < p1->P_RTIME_USEC)
142 return 1;
143
144 return p2->p_pid > p1->p_pid; /* Nonsense */
145 }
146 #endif /* STANDALONE */
147