common/lib/libutil/proc_compare.c

   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 */