Annotation of src/usr.bin/w/proc_compare.c, Revision 1.12
1.12 ! guenther 1: /* $OpenBSD: proc_compare.c,v 1.11 2009/10/27 23:59:49 deraadt Exp $ */
1.2 deraadt 2:
1.1 deraadt 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.
1.6 millert 15: * 3. Neither the name of the University nor the names of its contributors
1.1 deraadt 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:
32: #include <sys/param.h>
33: #include <sys/time.h>
1.8 millert 34: #include <sys/sysctl.h>
1.1 deraadt 35:
36: #include "extern.h"
37:
38: /*
39: * Returns 1 if p2 is "better" than p1
40: *
41: * The algorithm for picking the "interesting" process is thus:
42: *
43: * 1) Only foreground processes are eligible - implied.
44: * 2) Runnable processes are favored over anything else. The runner
45: * with the highest cpu utilization is picked (p_estcpu). Ties are
46: * broken by picking the highest pid.
47: * 3) The sleeper with the shortest sleep time is next. With ties,
48: * we pick out just "short-term" sleepers (P_SINTR == 0).
49: * 4) Further ties are broken by picking the highest pid.
50: *
51: * If you change this, be sure to consider making the change in the kernel
52: * too (^T in kern/tty.c).
53: *
54: * TODO - consider whether pctcpu should be used.
55: */
56:
1.9 markus 57: #define ISRUN(p) (((p)->p_stat == SRUN) || ((p)->p_stat == SIDL) || \
58: ((p)->p_stat == SONPROC))
1.1 deraadt 59: #define TESTAB(a, b) ((a)<<1 | (b))
60: #define ONLYA 2
61: #define ONLYB 1
62: #define BOTH 3
63:
64: int
1.12 ! guenther 65: proc_compare(const struct kinfo_proc *p1, const struct kinfo_proc *p2)
1.1 deraadt 66: {
67: if (p1 == NULL)
68: return (1);
69: /*
70: * see if at least one of them is runnable
71: */
72: switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
73: case ONLYA:
74: return (0);
75: case ONLYB:
76: return (1);
77: case BOTH:
78: /*
79: * tie - favor one with highest recent cpu utilization
80: */
81: if (p2->p_estcpu > p1->p_estcpu)
82: return (1);
83: if (p1->p_estcpu > p2->p_estcpu)
84: return (0);
85: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
86: }
87: /*
1.10 deraadt 88: * weed out zombies
1.1 deraadt 89: */
90: switch (TESTAB(p1->p_stat == SZOMB, p2->p_stat == SZOMB)) {
91: case ONLYA:
92: return (1);
93: case ONLYB:
94: return (0);
95: case BOTH:
96: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
97: }
98: /*
99: * pick the one with the smallest sleep time
100: */
101: if (p2->p_slptime > p1->p_slptime)
102: return (0);
103: if (p1->p_slptime > p2->p_slptime)
104: return (1);
105: /*
106: * favor one sleeping in a non-interruptible sleep
107: */
108: if (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
109: return (1);
110: if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
111: return (0);
112: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
113: }