Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bd53f96ca54a21c07e7a0ae1886fa623d370b85f
Commit:     bd53f96ca54a21c07e7a0ae1886fa623d370b85f
Parent:     4953198b6ce07b008b0f1c2edd41c9d027a118b4
Author:     Dmitry Adamushko <[EMAIL PROTECTED]>
AuthorDate: Tue May 8 00:33:06 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue May 8 11:15:17 2007 -0700

    sched: redundant reschedule when set_user_nice() boosts a prio of a task 
from the "expired" array
    
    - Make TASK_PREEMPTS_CURR(task, rq) return "true" only if the task's prio
      is higher than the current's one and the task is in the "active" array.
      This ensures we don't make redundant resched_task() calls when the task
      is in the "expired" array (as may happen now in set_user_prio(),
      rt_mutex_setprio() and pull_task() ) ;
    
    - generalise conditions for a call to resched_task() in set_user_nice(),
      rt_mutex_setprio() and sched_setscheduler()
    
    Signed-off-by: Dmitry Adamushko <[EMAIL PROTECTED]>
    Cc: Con Kolivas <[EMAIL PROTECTED]>
    Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 kernel/sched.c |   34 ++++++++++++++++------------------
 1 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index e60786e..be2706c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -169,7 +169,7 @@ unsigned long long __attribute__((weak)) sched_clock(void)
                (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
 
 #define TASK_PREEMPTS_CURR(p, rq) \
-       ((p)->prio < (rq)->curr->prio)
+       (((p)->prio < (rq)->curr->prio) && ((p)->array == (rq)->active))
 
 #define SCALE_PRIO(x, prio) \
        max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
@@ -4076,13 +4076,13 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
        struct prio_array *array;
        unsigned long flags;
        struct rq *rq;
-       int oldprio;
+       int delta;
 
        BUG_ON(prio < 0 || prio > MAX_PRIO);
 
        rq = task_rq_lock(p, &flags);
 
-       oldprio = p->prio;
+       delta = prio - p->prio;
        array = p->array;
        if (array)
                dequeue_task(p, array);
@@ -4098,13 +4098,11 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
                enqueue_task(p, array);
                /*
                 * Reschedule if we are currently running on this runqueue and
-                * our priority decreased, or if we are not currently running on
-                * this runqueue and our priority is higher than the current's
+                * our priority decreased, or if our priority became higher
+                * than the current's.
                 */
-               if (task_running(rq, p)) {
-                       if (p->prio > oldprio)
-                               resched_task(rq->curr);
-               } else if (TASK_PREEMPTS_CURR(p, rq))
+               if (TASK_PREEMPTS_CURR(p, rq) ||
+                               (delta > 0 && task_running(rq, p)))
                        resched_task(rq->curr);
        }
        task_rq_unlock(rq, &flags);
@@ -4152,10 +4150,12 @@ void set_user_nice(struct task_struct *p, long nice)
                enqueue_task(p, array);
                inc_raw_weighted_load(rq, p);
                /*
-                * If the task increased its priority or is running and
-                * lowered its priority, then reschedule its CPU:
+                * Reschedule if we are currently running on this runqueue and
+                * our priority decreased, or if our priority became higher
+                * than the current's.
                 */
-               if (delta < 0 || (delta > 0 && task_running(rq, p)))
+               if (TASK_PREEMPTS_CURR(p, rq) ||
+                               (delta > 0 && task_running(rq, p)))
                        resched_task(rq->curr);
        }
 out_unlock:
@@ -4382,13 +4382,11 @@ recheck:
                __activate_task(p, rq);
                /*
                 * Reschedule if we are currently running on this runqueue and
-                * our priority decreased, or if we are not currently running on
-                * this runqueue and our priority is higher than the current's
+                * our priority decreased, or our priority became higher
+                * than the current's.
                 */
-               if (task_running(rq, p)) {
-                       if (p->prio > oldprio)
-                               resched_task(rq->curr);
-               } else if (TASK_PREEMPTS_CURR(p, rq))
+               if (TASK_PREEMPTS_CURR(p, rq) ||
+                               (task_running(rq, p) && p->prio > oldprio))
                        resched_task(rq->curr);
        }
        __task_rq_unlock(rq);
-
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