GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: usr.bin/w/proc_compare.c Lines: 0 23 0.0 %
Date: 2016-12-06 Branches: 0 28 0.0 %

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/*	$OpenBSD: proc_compare.c,v 1.15 2015/01/16 06:40:14 deraadt 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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#include <sys/param.h>	/* MAXCOMLEN */
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#include <sys/proc.h>
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#include <sys/sysctl.h>
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#include <sys/time.h>
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#include "extern.h"
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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 (p_estcpu).  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 highest pid.
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 *
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 * If you change this, be sure to consider making the change in the kernel
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 * too (^T in kern/tty.c).
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 *
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 * TODO - consider whether pctcpu should be used.
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 */
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#define ISRUN(p)	(((p)->p_stat == SRUN) || ((p)->p_stat == SIDL) || \
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			 ((p)->p_stat == SONPROC))
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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 struct kinfo_proc *p1, const struct kinfo_proc *p2)
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{
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	if (p1 == NULL)
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		return (1);
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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 (p2->p_estcpu > p1->p_estcpu)
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			return (1);
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		if (p1->p_estcpu > p2->p_estcpu)
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			return (0);
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		return (p2->p_pid > p1->p_pid);	/* tie - return highest pid */
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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(p1->p_stat == SDEAD, p2->p_stat == SDEAD)) {
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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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		return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
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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 (p2->p_slptime > p1->p_slptime)
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		return (0);
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	if (p1->p_slptime > p2->p_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 (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
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		return (1);
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	if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
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		return (0);
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	return (p2->p_pid > p1->p_pid);		/* tie - return highest pid */
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}