Annotation of src/usr.bin/w/proc_compare.c, Revision 1.13
1.13 ! millert 1: /* $OpenBSD: proc_compare.c,v 1.12 2011/04/10 03:20:59 guenther 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>
1.13 ! millert 33: #include <sys/proc.h>
! 34: #include <sys/sysctl.h>
1.1 deraadt 35: #include <sys/time.h>
36:
37: #include "extern.h"
38:
39: /*
40: * Returns 1 if p2 is "better" than p1
41: *
42: * The algorithm for picking the "interesting" process is thus:
43: *
44: * 1) Only foreground processes are eligible - implied.
45: * 2) Runnable processes are favored over anything else. The runner
46: * with the highest cpu utilization is picked (p_estcpu). Ties are
47: * broken by picking the highest pid.
48: * 3) The sleeper with the shortest sleep time is next. With ties,
49: * we pick out just "short-term" sleepers (P_SINTR == 0).
50: * 4) Further ties are broken by picking the highest pid.
51: *
52: * If you change this, be sure to consider making the change in the kernel
53: * too (^T in kern/tty.c).
54: *
55: * TODO - consider whether pctcpu should be used.
56: */
57:
1.9 markus 58: #define ISRUN(p) (((p)->p_stat == SRUN) || ((p)->p_stat == SIDL) || \
59: ((p)->p_stat == SONPROC))
1.1 deraadt 60: #define TESTAB(a, b) ((a)<<1 | (b))
61: #define ONLYA 2
62: #define ONLYB 1
63: #define BOTH 3
64:
65: int
1.12 guenther 66: proc_compare(const struct kinfo_proc *p1, const struct kinfo_proc *p2)
1.1 deraadt 67: {
68: if (p1 == NULL)
69: return (1);
70: /*
71: * see if at least one of them is runnable
72: */
73: switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
74: case ONLYA:
75: return (0);
76: case ONLYB:
77: return (1);
78: case BOTH:
79: /*
80: * tie - favor one with highest recent cpu utilization
81: */
82: if (p2->p_estcpu > p1->p_estcpu)
83: return (1);
84: if (p1->p_estcpu > p2->p_estcpu)
85: return (0);
86: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
87: }
88: /*
1.10 deraadt 89: * weed out zombies
1.1 deraadt 90: */
91: switch (TESTAB(p1->p_stat == SZOMB, p2->p_stat == SZOMB)) {
92: case ONLYA:
93: return (1);
94: case ONLYB:
95: return (0);
96: case BOTH:
97: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
98: }
99: /*
100: * pick the one with the smallest sleep time
101: */
102: if (p2->p_slptime > p1->p_slptime)
103: return (0);
104: if (p1->p_slptime > p2->p_slptime)
105: return (1);
106: /*
107: * favor one sleeping in a non-interruptible sleep
108: */
109: if (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
110: return (1);
111: if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
112: return (0);
113: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
114: }