w/proc_compare.c

   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.
  13  * 3. Neither the name of the University nor the names of its contributors
  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.
  28  */
  29
  30 #if 0
  31 #ifndef lint
  32 static char sccsid[] = "@(#)proc_compare.c      8.2 (Berkeley) 9/23/93";
  33 #endif /* not lint */
  34 #endif
  35
  36 #include <sys/cdefs.h>
  37 #ifndef __APPLE__
  38 __FBSDID("$FreeBSD: src/usr.bin/w/proc_compare.c,v 1.9 2004/04/14 09:34:17 bde Exp $");
  39 #endif
  40
  41 #include <sys/param.h>
  42 #ifdef __APPLE__
  43 #include <sys/time.h>
  44 #endif
  45 #include <sys/proc.h>
  46 #include <sys/time.h>
  47 #include <sys/user.h>
  48
  49 #include "extern.h"
  50
  51 /*
  52  * Returns 1 if p2 is "better" than p1
  53  *
  54  * The algorithm for picking the "interesting" process is thus:
  55  *
  56  *      1) Only foreground processes are eligible - implied.
  57  *      2) Runnable processes are favored over anything else.  The runner
  58  *         with the highest cpu utilization is picked (p_estcpu).  Ties are
  59  *         broken by picking the highest pid.
  60  *      3) The sleeper with the shortest sleep time is next.  With ties,
  61  *         we pick out just "short-term" sleepers (TDF_SINTR == 0).
  62  *      4) Further ties are broken by picking the highest pid.
  63  *
  64  * If you change this, be sure to consider making the change in the kernel
  65  * too (^T in kern/tty.c).
  66  *
  67  * TODO - consider whether pctcpu should be used.
  68  */
  69
  70 #if !HAVE_KVM
  71 #define ki_estcpu       p_estcpu
  72 #define ki_pid          p_pid
  73 #define ki_slptime      p_slptime
  74 #define ki_stat         p_stat
  75 #define ki_tdflags      p_tdflags
  76 #endif
  77
  78 #define ISRUN(p)        (((p)->ki_stat == SRUN) || ((p)->ki_stat == SIDL))
  79 #define TESTAB(a, b)    ((a)<<1 | (b))
  80 #define ONLYA   2
  81 #define ONLYB   1
  82 #define BOTH    3
  83
  84 #if HAVE_KVM
  85 int
  86 proc_compare(struct kinfo_proc *p1, struct kinfo_proc *p2)
  87 {
  88 #else
  89 int
  90 proc_compare(struct kinfo_proc *arg1, struct kinfo_proc *arg2)
  91 {
  92         struct extern_proc* p1 = &arg1->kp_proc;
  93         struct extern_proc* p2 = &arg2->kp_proc;
  94 #endif
  95
  96         if (p1 == NULL)
  97                 return (1);
  98         /*
  99          * see if at least one of them is runnable
 100          */
 101         switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
 102         case ONLYA:
 103                 return (0);
 104         case ONLYB:
 105                 return (1);
 106         case BOTH:
 107                 /*
 108                  * tie - favor one with highest recent cpu utilization
 109                  */
 110                 if (p2->ki_estcpu > p1->ki_estcpu)
 111                         return (1);
 112                 if (p1->ki_estcpu > p2->ki_estcpu)
 113                         return (0);
 114                 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */
 115         }
 116         /*
 117          * weed out zombies
 118          */
 119         switch (TESTAB(p1->ki_stat == SZOMB, p2->ki_stat == SZOMB)) {
 120         case ONLYA:
 121                 return (1);
 122         case ONLYB:
 123                 return (0);
 124         case BOTH:
 125                 return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */
 126         }
 127         /*
 128          * pick the one with the smallest sleep time
 129          */
 130         if (p2->ki_slptime > p1->ki_slptime)
 131                 return (0);
 132         if (p1->ki_slptime > p2->ki_slptime)
 133                 return (1);
 134 #ifndef __APPLE__
 135         /*
 136          * favor one sleeping in a non-interruptible sleep
 137          */
 138         if (p1->ki_tdflags & TDF_SINTR && (p2->ki_tdflags & TDF_SINTR) == 0)
 139                 return (1);
 140         if (p2->ki_tdflags & TDF_SINTR && (p1->ki_tdflags & TDF_SINTR) == 0)
 141                 return (0);
 142 #endif
 143         return (p2->ki_pid > p1->ki_pid);       /* tie - return highest pid */
 144 }