mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-11 09:50:12 +00:00
121 lines
3.9 KiB
C
121 lines
3.9 KiB
C
/*-
|
|
* 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. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. 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 lint
|
|
static char sccsid[] = "@(#)proc_compare.c 8.2 (Berkeley) 9/23/93";
|
|
#endif /* not lint */
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/time.h>
|
|
#include <sys/proc.h>
|
|
|
|
#include "extern.h"
|
|
|
|
/*
|
|
* 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 (p_estcpu). 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 highest pid.
|
|
*
|
|
* If you change this, be sure to consider making the change in the kernel
|
|
* too (^T in kern/tty.c).
|
|
*
|
|
* TODO - consider whether pctcpu should be used.
|
|
*/
|
|
|
|
#define ISRUN(p) (((p)->p_stat == SRUN) || ((p)->p_stat == SIDL))
|
|
#define TESTAB(a, b) ((a)<<1 | (b))
|
|
#define ONLYA 2
|
|
#define ONLYB 1
|
|
#define BOTH 3
|
|
|
|
int
|
|
proc_compare(p1, p2)
|
|
register struct proc *p1, *p2;
|
|
{
|
|
|
|
if (p1 == NULL)
|
|
return (1);
|
|
/*
|
|
* 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 (p2->p_estcpu > p1->p_estcpu)
|
|
return (1);
|
|
if (p1->p_estcpu > p2->p_estcpu)
|
|
return (0);
|
|
return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
|
|
}
|
|
/*
|
|
* weed out zombies
|
|
*/
|
|
switch (TESTAB(p1->p_stat == SZOMB, p2->p_stat == SZOMB)) {
|
|
case ONLYA:
|
|
return (1);
|
|
case ONLYB:
|
|
return (0);
|
|
case BOTH:
|
|
return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
|
|
}
|
|
/*
|
|
* pick the one with the smallest sleep time
|
|
*/
|
|
if (p2->p_slptime > p1->p_slptime)
|
|
return (0);
|
|
if (p1->p_slptime > p2->p_slptime)
|
|
return (1);
|
|
/*
|
|
* favor one sleeping in a non-interruptible sleep
|
|
*/
|
|
if (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
|
|
return (1);
|
|
if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
|
|
return (0);
|
|
return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
|
|
}
|