* Copyright (c) 1990 The Regents of the University of California.
* %sccs.include.redist.c%
static char sccsid
[] = "@(#)proc_compare.c 5.5 (Berkeley) %G%";
* 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
* 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
#define isrun(p) (((p)->p_stat == SRUN) || ((p)->p_stat == SIDL))
#define TESTAB(a, b) ((a)<<1 | (b))
register struct proc
*p1
, *p2
;
* see if at least one of them is runnable
switch (TESTAB(isrun(p1
), isrun(p2
))) {
* tie - favor one with highest recent cpu utilization
if (p2
->p_cpu
> p1
->p_cpu
)
if (p1
->p_cpu
> p2
->p_cpu
)
return (p2
->p_pid
> p1
->p_pid
); /* tie - return highest pid */
switch (TESTAB(p1
->p_stat
== SZOMB
, p2
->p_stat
== SZOMB
)) {
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
)
if (p1
->p_slptime
> p2
->p_slptime
)
* favor one sleeping in a non-interruptible sleep
if (p1
->p_flag
&SSINTR
&& (p2
->p_flag
&SSINTR
) == 0)
if (p2
->p_flag
&SSINTR
&& (p1
->p_flag
&SSINTR
) == 0)
return(p2
->p_pid
> p1
->p_pid
); /* tie - return highest pid */