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/* $NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $ */
/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _STANDALONE
# ifndef _KERNEL
# if HAVE_NBTOOL_CONFIG_H
# include "nbtool_config.h"
# endif
# include <sys/cdefs.h>
# if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $");
# endif
# include <sys/types.h>
# include <sys/inttypes.h>
# include <sys/sysctl.h>
# include <stdio.h>
# include <util.h>
# include <errno.h>
# define PROC struct kinfo_proc2
# define LWP struct kinfo_lwp
# define P_RTIME_SEC p_rtime_sec
# define P_RTIME_USEC p_rtime_usec
# else
# include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: proc_compare.c,v 1.1 2011/10/21 02:09:00 christos Exp $");
# include <sys/param.h>
# include <sys/inttypes.h>
# include <sys/systm.h>
# include <sys/proc.h>
# include <sys/lwp.h>
# include <lib/libkern/libkern.h>
# define PROC struct proc
# define LWP struct lwp
# define P_RTIME_SEC p_rtime.sec
# define P_RTIME_USEC p_rtime.frac
# endif
/*
* Returns 1 if p2 is "better" than p1
*
* The algorithm for picking the "interesting" process is thus:
*
* 1) Only foreground processes are eligible - implied.
* 2) Runnable processes are favored over anything else. The runner
* with the highest CPU utilization is picked (l_pctcpu). Ties are
* broken by picking the highest pid.
* 3) The sleeper with the shortest sleep time is next. With ties,
* we pick out just "short-term" sleepers (P_SINTR == 0).
* 4) Further ties are broken by picking the one started last.
* 5) Finally the one with the biggest pid wins, but that is nonsense
* because of pid randomization.
*/
#define ISRUN(p) ((p)->p_nrlwps > 0)
#define TESTAB(a, b) (((a) << 1) | (b))
#define ONLYA 2
#define ONLYB 1
#define BOTH 3
int
proc_compare(const PROC *p1, const LWP *l1, const PROC *p2, const LWP *l2)
{
/*
* see if at least one of them is runnable
*/
switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
case ONLYA:
return 0;
case ONLYB:
return 1;
case BOTH:
/*
* tie - favor one with highest recent CPU utilization
*/
if (l2->l_pctcpu > l1->l_pctcpu)
return 1;
goto out;
}
/*
* weed out zombies
*/
switch (TESTAB(P_ZOMBIE(p1), P_ZOMBIE(p2))) {
case ONLYA:
return 1;
case ONLYB:
return 0;
case BOTH:
goto out;
}
/*
* pick the one with the smallest sleep time
*/
if (l1->l_slptime < l2->l_slptime)
return 0;
if (l2->l_slptime < l1->l_slptime)
return 1;
/*
* favor one sleeping in a non-interruptible sleep
*/
if ((l1->l_flag & LW_SINTR) && (l2->l_flag & LW_SINTR) == 0)
return 0;
if ((l2->l_flag & LW_SINTR) && (l1->l_flag & LW_SINTR) == 0)
return 1;
out:
/* tie, return the one with the smallest realtime */
if (p1->P_RTIME_SEC < p2->P_RTIME_SEC)
return 0;
if (p2->P_RTIME_SEC < p1->P_RTIME_SEC)
return 1;
if (p1->P_RTIME_USEC < p2->P_RTIME_USEC)
return 0;
if (p2->P_RTIME_USEC < p1->P_RTIME_USEC)
return 1;
return p2->p_pid > p1->p_pid; /* Nonsense */
}
#endif /* STANDALONE */
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