fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
122 lines
3.8 KiB
C
122 lines
3.8 KiB
C
/*-
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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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#if 0
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#ifndef lint
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static char sccsid[] = "@(#)proc_compare.c 8.2 (Berkeley) 9/23/93";
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#endif /* not lint */
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#endif
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/proc.h>
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#include <sys/time.h>
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#include <sys/user.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 (TDF_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)->ki_stat == SRUN) || ((p)->ki_stat == SIDL))
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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(struct kinfo_proc *p1, 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->ki_estcpu > p1->ki_estcpu)
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return (1);
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if (p1->ki_estcpu > p2->ki_estcpu)
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return (0);
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return (p2->ki_pid > p1->ki_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->ki_stat == SZOMB, p2->ki_stat == SZOMB)) {
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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->ki_pid > p1->ki_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->ki_slptime > p1->ki_slptime)
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return (0);
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if (p1->ki_slptime > p2->ki_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->ki_tdflags & TDF_SINTR && (p2->ki_tdflags & TDF_SINTR) == 0)
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return (1);
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if (p2->ki_tdflags & TDF_SINTR && (p1->ki_tdflags & TDF_SINTR) == 0)
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return (0);
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return (p2->ki_pid > p1->ki_pid); /* tie - return highest pid */
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}
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