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