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984263bc MD |
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. | |
dc71b7ab | 13 | * 3. Neither the name of the University nor the names of its contributors |
984263bc MD |
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. | |
1de703da MD |
28 | * |
29 | * @(#)proc_compare.c 8.2 (Berkeley) 9/23/93 | |
1d1731fa | 30 | * |
416d05d7 | 31 | * $DragonFly: src/usr.bin/w/proc_compare.c,v 1.9 2007/02/18 16:15:24 corecode Exp $ |
984263bc MD |
32 | */ |
33 | ||
e0ecab34 | 34 | #include <sys/user.h> |
984263bc MD |
35 | #include <sys/param.h> |
36 | #include <sys/time.h> | |
984263bc MD |
37 | |
38 | #include "extern.h" | |
39 | ||
40 | /* | |
41 | * Returns 1 if p2 is "better" than p1 | |
42 | * | |
43 | * The algorithm for picking the "interesting" process is thus: | |
44 | * | |
45 | * 1) Only foreground processes are eligible - implied. | |
46 | * 2) Runnable processes are favored over anything else. The runner | |
47 | * with the highest cpu utilization is picked (p_estcpu). Ties are | |
48 | * broken by picking the highest pid. | |
49 | * 3) The sleeper with the shortest sleep time is next. With ties, | |
9a379a4a | 50 | * we pick out just "short-term" sleepers (LWP_SINTR == 0). |
984263bc MD |
51 | * 4) Further ties are broken by picking the highest pid. |
52 | * | |
53 | * If you change this, be sure to consider making the change in the kernel | |
54 | * too (^T in kern/tty.c). | |
55 | * | |
56 | * TODO - consider whether pctcpu should be used. | |
57 | */ | |
58 | ||
164b8401 | 59 | #define ISRUN(p) ((p)->kp_lwp.kl_stat == LSRUN) |
984263bc MD |
60 | #define TESTAB(a, b) ((a)<<1 | (b)) |
61 | #define ONLYA 2 | |
62 | #define ONLYB 1 | |
63 | #define BOTH 3 | |
64 | ||
65 | int | |
5dfd06ac | 66 | proc_compare(struct kinfo_proc *p1, struct kinfo_proc *p2) |
984263bc MD |
67 | { |
68 | ||
69 | if (p1 == NULL) | |
70 | return (1); | |
71 | /* | |
72 | * see if at least one of them is runnable | |
73 | */ | |
74 | switch (TESTAB(ISRUN(p1), ISRUN(p2))) { | |
75 | case ONLYA: | |
76 | return (0); | |
77 | case ONLYB: | |
78 | return (1); | |
79 | case BOTH: | |
80 | /* | |
81 | * tie - favor one with highest recent cpu utilization | |
82 | */ | |
5dfd06ac | 83 | if (p2->kp_lwp.kl_estcpu > p1->kp_lwp.kl_estcpu) |
984263bc | 84 | return (1); |
5dfd06ac | 85 | if (p1->kp_lwp.kl_estcpu > p2->kp_lwp.kl_estcpu) |
984263bc | 86 | return (0); |
5dfd06ac | 87 | return (p2->kp_pid > p1->kp_pid); /* tie - return highest pid */ |
984263bc MD |
88 | } |
89 | /* | |
90 | * weed out zombies | |
91 | */ | |
416d05d7 | 92 | switch (TESTAB(p1->kp_stat == SZOMB, p2->kp_stat == SZOMB)) { |
984263bc MD |
93 | case ONLYA: |
94 | return (1); | |
95 | case ONLYB: | |
96 | return (0); | |
97 | case BOTH: | |
5dfd06ac | 98 | return (p2->kp_pid > p1->kp_pid); /* tie - return highest pid */ |
984263bc MD |
99 | } |
100 | /* | |
101 | * pick the one with the smallest sleep time | |
102 | */ | |
5dfd06ac | 103 | if (p2->kp_lwp.kl_slptime > p1->kp_lwp.kl_slptime) |
984263bc | 104 | return (0); |
5dfd06ac | 105 | if (p1->kp_lwp.kl_slptime > p2->kp_lwp.kl_slptime) |
984263bc MD |
106 | return (1); |
107 | /* | |
108 | * favor one sleeping in a non-interruptible sleep | |
109 | */ | |
9a379a4a | 110 | if (p1->kp_lwp.kl_flags & LWP_SINTR && (p2->kp_lwp.kl_flags & LWP_SINTR) == 0) |
984263bc | 111 | return (1); |
9a379a4a | 112 | if (p2->kp_lwp.kl_flags & LWP_SINTR && (p1->kp_lwp.kl_flags & LWP_SINTR) == 0) |
984263bc | 113 | return (0); |
5dfd06ac | 114 | return (p2->kp_pid > p1->kp_pid); /* tie - return highest pid */ |
984263bc | 115 | } |