NetBSD/usr.bin/w/proc_compare.c

126 lines
3.9 KiB
C

/*-
* Copyright (c) 1990 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[] = "from: @(#)proc_compare.c 5.4 (Berkeley) 2/7/91";*/
static char rcsid[] = "$Id: proc_compare.c,v 1.2 1993/08/01 18:03:16 mycroft Exp $";
#endif /* not lint */
/*
* Returns 1 if p2 is more active than p1
*
* The algorithm for picking the "more active" process is thus:
*
* 1) Runnable processes are favored over anything
* else. The runner with the highest cpu
* utilization is picked (p_cpu). Ties are
* broken by picking the highest pid.
* 2) Next, the sleeper with the shortest sleep
* time is favored. With ties, we pick out
* just short-term sleepers (p_pri <= PZERO).
* Further ties are broken by picking the highest
* pid.
*
* NOTE - 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
*
*/
#include <sys/param.h>
#include <sys/time.h>
#include <sys/proc.h>
#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
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_cpu > p1->p_cpu)
return (1);
if (p1->p_cpu > p2->p_cpu)
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&SSINTR && (p2->p_flag&SSINTR) == 0)
return (1);
if (p2->p_flag&SSINTR && (p1->p_flag&SSINTR) == 0)
return (0);
return(p2->p_pid > p1->p_pid); /* tie - return highest pid */
}