2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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.
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
35 #include <sys/cdefs.h>
36 #include <sys/param.h>
44 * Returns 1 if p2 is "better" than p1
46 * The algorithm for picking the "interesting" process is thus:
48 * 1) Only foreground processes are eligible - implied.
49 * 2) Runnable processes are favored over anything else. The runner
50 * with the highest cpu utilization is picked (p_estcpu). Ties are
51 * broken by picking the highest pid.
52 * 3) The sleeper with the shortest sleep time is next. With ties,
53 * we pick out just "short-term" sleepers (TDF_SINTR == 0).
54 * 4) Further ties are broken by picking the highest pid.
56 * If you change this, be sure to consider making the change in the kernel
57 * too (^T in kern/tty.c).
59 * TODO - consider whether pctcpu should be used.
62 #define ISRUN(p) (((p)->ki_stat == SRUN) || ((p)->ki_stat == SIDL))
63 #define TESTAB(a, b) ((a)<<1 | (b))
69 proc_compare(struct kinfo_proc *p1, struct kinfo_proc *p2)
75 * see if at least one of them is runnable
77 switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
84 * tie - favor one with highest recent cpu utilization
86 if (p2->ki_estcpu > p1->ki_estcpu)
88 if (p1->ki_estcpu > p2->ki_estcpu)
90 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */
95 switch (TESTAB(p1->ki_stat == SZOMB, p2->ki_stat == SZOMB)) {
101 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */
104 * pick the one with the smallest sleep time
106 if (p2->ki_slptime > p1->ki_slptime)
108 if (p1->ki_slptime > p2->ki_slptime)
111 * favor one sleeping in a non-interruptible sleep
113 if (p1->ki_tdflags & TDF_SINTR && (p2->ki_tdflags & TDF_SINTR) == 0)
115 if (p2->ki_tdflags & TDF_SINTR && (p1->ki_tdflags & TDF_SINTR) == 0)
117 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */