| 1 | /* $NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $ */ |
| 2 | |
| 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. |
| 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. |
| 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 | #ifndef _STANDALONE |
| 32 | # ifndef _KERNEL |
| 33 | |
| 34 | # if HAVE_NBTOOL_CONFIG_H |
| 35 | # include "nbtool_config.h" |
| 36 | # endif |
| 37 | |
| 38 | # include <sys/cdefs.h> |
| 39 | # if defined(LIBC_SCCS) && !defined(lint) |
| 40 | __RCSID("$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $" ); |
| 41 | # endif |
| 42 | |
| 43 | # include <sys/types.h> |
| 44 | # include <sys/inttypes.h> |
| 45 | # include <sys/sysctl.h> |
| 46 | # include <stdio.h> |
| 47 | # include <util.h> |
| 48 | # include <errno.h> |
| 49 | # define PROC struct kinfo_proc2 |
| 50 | # define LWP struct kinfo_lwp |
| 51 | # define P_RTIME_SEC p_rtime_sec |
| 52 | # define P_RTIME_USEC p_rtime_usec |
| 53 | # else |
| 54 | # include <sys/cdefs.h> |
| 55 | __KERNEL_RCSID(0, "$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $" ); |
| 56 | # include <sys/param.h> |
| 57 | # include <sys/inttypes.h> |
| 58 | # include <sys/systm.h> |
| 59 | # include <sys/proc.h> |
| 60 | # include <sys/lwp.h> |
| 61 | # include <lib/libkern/libkern.h> |
| 62 | # define PROC struct proc |
| 63 | # define LWP struct lwp |
| 64 | # define P_RTIME_SEC p_rtime.sec |
| 65 | # define P_RTIME_USEC p_rtime.frac |
| 66 | # endif |
| 67 | /* |
| 68 | * Returns 1 if p2 is "better" than p1 |
| 69 | * |
| 70 | * The algorithm for picking the "interesting" process is thus: |
| 71 | * |
| 72 | * 1) Only foreground processes are eligible - implied. |
| 73 | * 2) Runnable processes are favored over anything else. The runner |
| 74 | * with the highest CPU utilization is picked (l_pctcpu). Ties are |
| 75 | * broken by picking the highest pid. |
| 76 | * 3) The sleeper with the shortest sleep time is next. With ties, |
| 77 | * we pick out just "short-term" sleepers (P_SINTR == 0). |
| 78 | * 4) Further ties are broken by picking the one started last. |
| 79 | * 5) Finally the one with the biggest pid wins, but that is nonsense |
| 80 | * because of pid randomization. |
| 81 | */ |
| 82 | #define ISRUN(p) ((p)->p_nrlwps > 0) |
| 83 | #define TESTAB(a, b) (((a) << 1) | (b)) |
| 84 | #define ONLYA 2 |
| 85 | #define ONLYB 1 |
| 86 | #define BOTH 3 |
| 87 | |
| 88 | int |
| 89 | proc_compare(const PROC *p1, const LWP *l1, const PROC *p2, const LWP *l2) |
| 90 | { |
| 91 | /* |
| 92 | * see if at least one of them is runnable |
| 93 | */ |
| 94 | switch (TESTAB(ISRUN(p1), ISRUN(p2))) { |
| 95 | case ONLYA: |
| 96 | return 0; |
| 97 | case ONLYB: |
| 98 | return 1; |
| 99 | case BOTH: |
| 100 | /* |
| 101 | * tie - favor one with highest recent CPU utilization |
| 102 | */ |
| 103 | if (l2->l_pctcpu > l1->l_pctcpu) |
| 104 | return 1; |
| 105 | goto out; |
| 106 | } |
| 107 | /* |
| 108 | * weed out zombies |
| 109 | */ |
| 110 | switch (TESTAB(P_ZOMBIE(p1), P_ZOMBIE(p2))) { |
| 111 | case ONLYA: |
| 112 | return 1; |
| 113 | case ONLYB: |
| 114 | return 0; |
| 115 | case BOTH: |
| 116 | goto out; |
| 117 | } |
| 118 | /* |
| 119 | * pick the one with the smallest sleep time |
| 120 | */ |
| 121 | if (l1->l_slptime < l2->l_slptime) |
| 122 | return 0; |
| 123 | if (l2->l_slptime < l1->l_slptime) |
| 124 | return 1; |
| 125 | |
| 126 | /* |
| 127 | * favor one sleeping in a non-interruptible sleep |
| 128 | */ |
| 129 | if ((l1->l_flag & LW_SINTR) && (l2->l_flag & LW_SINTR) == 0) |
| 130 | return 0; |
| 131 | if ((l2->l_flag & LW_SINTR) && (l1->l_flag & LW_SINTR) == 0) |
| 132 | return 1; |
| 133 | out: |
| 134 | /* tie, return the one with the smallest realtime */ |
| 135 | if (p1->P_RTIME_SEC < p2->P_RTIME_SEC) |
| 136 | return 0; |
| 137 | if (p2->P_RTIME_SEC < p1->P_RTIME_SEC) |
| 138 | return 1; |
| 139 | if (p1->P_RTIME_USEC < p2->P_RTIME_USEC) |
| 140 | return 0; |
| 141 | if (p2->P_RTIME_USEC < p1->P_RTIME_USEC) |
| 142 | return 1; |
| 143 | |
| 144 | return p2->p_pid > p1->p_pid; /* Nonsense */ |
| 145 | } |
| 146 | #endif /* STANDALONE */ |
| 147 | |