Annotation of src/usr.bin/w/proc_compare.c, Revision 1.9
1.9 ! markus 1: /* $OpenBSD: proc_compare.c,v 1.8 2004/01/08 18:14:51 millert 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: #ifndef lint
1.3 millert 33: #if 0
1.1 deraadt 34: static char sccsid[] = "@(#)proc_compare.c 8.2 (Berkeley) 9/23/93";
1.3 millert 35: #else
1.9 ! markus 36: static char *rcsid = "$OpenBSD: proc_compare.c,v 1.8 2004/01/08 18:14:51 millert Exp $";
1.3 millert 37: #endif
1.1 deraadt 38: #endif /* not lint */
39:
40: #include <sys/param.h>
41: #include <sys/time.h>
1.8 millert 42: #include <sys/sysctl.h>
1.1 deraadt 43:
44: #include "extern.h"
45:
46: /*
47: * Returns 1 if p2 is "better" than p1
48: *
49: * The algorithm for picking the "interesting" process is thus:
50: *
51: * 1) Only foreground processes are eligible - implied.
52: * 2) Runnable processes are favored over anything else. The runner
53: * with the highest cpu utilization is picked (p_estcpu). Ties are
54: * broken by picking the highest pid.
55: * 3) The sleeper with the shortest sleep time is next. With ties,
56: * we pick out just "short-term" sleepers (P_SINTR == 0).
57: * 4) Further ties are broken by picking the highest pid.
58: *
59: * If you change this, be sure to consider making the change in the kernel
60: * too (^T in kern/tty.c).
61: *
62: * TODO - consider whether pctcpu should be used.
63: */
64:
1.9 ! markus 65: #define ISRUN(p) (((p)->p_stat == SRUN) || ((p)->p_stat == SIDL) || \
! 66: ((p)->p_stat == SONPROC))
1.1 deraadt 67: #define TESTAB(a, b) ((a)<<1 | (b))
68: #define ONLYA 2
69: #define ONLYB 1
70: #define BOTH 3
71:
72: int
1.8 millert 73: proc_compare(const struct kinfo_proc2 *p1, const struct kinfo_proc2 *p2)
1.1 deraadt 74: {
75: if (p1 == NULL)
76: return (1);
77: /*
78: * see if at least one of them is runnable
79: */
80: switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
81: case ONLYA:
82: return (0);
83: case ONLYB:
84: return (1);
85: case BOTH:
86: /*
87: * tie - favor one with highest recent cpu utilization
88: */
89: if (p2->p_estcpu > p1->p_estcpu)
90: return (1);
91: if (p1->p_estcpu > p2->p_estcpu)
92: return (0);
93: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
94: }
95: /*
96: * weed out zombies
97: */
98: switch (TESTAB(p1->p_stat == SZOMB, p2->p_stat == SZOMB)) {
99: case ONLYA:
100: return (1);
101: case ONLYB:
102: return (0);
103: case BOTH:
104: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
105: }
106: /*
107: * pick the one with the smallest sleep time
108: */
109: if (p2->p_slptime > p1->p_slptime)
110: return (0);
111: if (p1->p_slptime > p2->p_slptime)
112: return (1);
113: /*
114: * favor one sleeping in a non-interruptible sleep
115: */
116: if (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
117: return (1);
118: if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
119: return (0);
120: return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
121: }
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