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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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} |