[src/trunk]: src/sys/kern extract broken proc_compare. lwp compares against s...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c1c92716eaf3
branches:  trunk
changeset: 770539:c1c92716eaf3
user:      christos <christos%NetBSD.org@localhost>
date:      Fri Oct 21 02:08:09 2011 +0000

description:
extract broken proc_compare. lwp compares against self.

diffstat:

 sys/kern/tty.c |  78 ++++++++-------------------------------------------------
 1 files changed, 12 insertions(+), 66 deletions(-)

diffs (123 lines):

diff -r 5d348b4151b8 -r c1c92716eaf3 sys/kern/tty.c
--- a/sys/kern/tty.c    Fri Oct 21 02:07:07 2011 +0000
+++ b/sys/kern/tty.c    Fri Oct 21 02:08:09 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tty.c,v 1.248 2011/09/24 00:05:38 christos Exp $       */
+/*     $NetBSD: tty.c,v 1.249 2011/10/21 02:08:09 christos Exp $       */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -63,7 +63,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.248 2011/09/24 00:05:38 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.249 2011/10/21 02:08:09 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -99,7 +99,7 @@
 static void    ttyrubo(struct tty *, int);
 static void    ttyprintf_nolock(struct tty *, const char *fmt, ...)
     __attribute__((__format__(__printf__,2,3)));
-static int     proc_compare(struct proc *, struct proc *);
+static int     proc_compare_wrapper(struct proc *, struct proc *);
 static void    ttysigintr(void *);
 
 /* Symbolic sleep message strings. */
@@ -2488,7 +2488,7 @@
                        } else
                                mutex_enter(p->p_lock);
                        oldpick = pick;
-                       if (proc_compare(pick, p))
+                       if (proc_compare_wrapper(pick, p))
                                pick = p;
                        mutex_exit(p->p_lock);
                        if (p->p_lock != oldpick->p_lock)
@@ -2594,26 +2594,11 @@
 }
 
 /*
- * 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 (l_pctcpu).  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.
+ * Returns 1 if p2 has a better chance being the active foreground process
+ * in a terminal instead of p1.
  */
-#define        ISRUN(p)        ((p)->p_nrlwps > 0)
-#define        TESTAB(a, b)    ((a)<<1 | (b))
-#define        ONLYA   2
-#define        ONLYB   1
-#define        BOTH    3
-
 static int
-proc_compare(struct proc *p1, struct proc *p2)
+proc_compare_wrapper(struct proc *p1, struct proc *p2)
 {
        lwp_t *l1, *l2;
 
@@ -2621,51 +2606,12 @@
        KASSERT(mutex_owned(p2->p_lock));
 
        if ((l1 = LIST_FIRST(&p1->p_lwps)) == NULL)
-               return (1);
+               return 1;
+
        if ((l2 = LIST_FIRST(&p2->p_lwps)) == NULL)
-               return (0);
-       /*
-        * 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 (l2->l_pctcpu > l1->l_pctcpu)
-                       return (1);
-               return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
-       }
-       /*
-        * weed out zombies
-        */
-       switch (TESTAB(P_ZOMBIE(p1), P_ZOMBIE(p2))) {
-       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 (l2->l_slptime > l2->l_slptime)
-               return (0);
-       if (l2->l_slptime > l2->l_slptime)
-               return (1);
-       /*
-        * favor one sleeping in a non-interruptible sleep
-        */
-       if (l2->l_flag & LW_SINTR && (l2->l_flag & LW_SINTR) == 0)
-               return (1);
-       if (l2->l_flag & LW_SINTR && (l2->l_flag & LW_SINTR) == 0)
-               return (0);
-       return (p2->p_pid > p1->p_pid);         /* tie - return highest pid */
+               return 0;
+
+       return proc_compare(p1, l1, p2, l2);
 }
 
 /*