From: Con Kolivas <kernel@kolivas.org>
Much simpler
include/linux/sched.h | 1 -
kernel/sched.c | 38 +++++++++-----------------------------
2 files changed, 9 insertions(+), 30 deletions(-)
diff -puN include/linux/sched.h~o16.2int include/linux/sched.h
--- 25/include/linux/sched.h~o16.2int 2003-08-16 02:12:29.000000000 -0700
+++ 25-akpm/include/linux/sched.h 2003-08-16 02:12:29.000000000 -0700
@@ -376,7 +376,6 @@ struct task_struct {
*/
struct task_struct *real_parent; /* real parent process (when being debugged) */
struct task_struct *parent; /* parent process */
- struct task_struct *waker; /* waker process */
struct list_head children; /* list of my children */
struct list_head sibling; /* linkage in my parent's children list */
struct task_struct *group_leader;
diff -puN kernel/sched.c~o16.2int kernel/sched.c
--- 25/kernel/sched.c~o16.2int 2003-08-16 02:12:29.000000000 -0700
+++ 25-akpm/kernel/sched.c 2003-08-16 02:12:29.000000000 -0700
@@ -143,6 +143,9 @@
#define VARYING_CREDIT(p) \
(!(HIGH_CREDIT(p) || LOW_CREDIT(p)))
+#define TASK_PREEMPTS_CURR(p, rq) \
+ ((p)->prio < (rq)->curr->prio)
+
/*
* BASE_TIMESLICE scales user-nice values [ -20 ... 19 ]
* to time slice values.
@@ -464,24 +467,15 @@ static inline void activate_task(task_t
* of time they spend on the runqueue, waiting for execution
* on a CPU, first time around:
*/
- if (in_interrupt()){
+ if (in_interrupt())
p->activated = 2;
- p->waker = p;
- } else {
+ else
/*
* Normal first-time wakeups get a credit too for on-runqueue
* time, but it will be weighted down:
*/
p->activated = 1;
- p->waker = current;
}
- } else {
- if (in_interrupt())
- p->waker = p;
- else
- p->waker = current;
- }
-
p->timestamp = now;
__activate_task(p, rq);
@@ -565,20 +559,6 @@ repeat:
}
#endif
-static inline int task_preempts_curr(task_t *p, runqueue_t *rq)
-{
- if (p->prio < rq->curr->prio) {
- /*
- * Prevent a task preempting it's own waker
- * to avoid starvation
- */
- if (unlikely(rq->curr == p->waker))
- return 0;
- return 1;
- }
- return 0;
-}
-
/***
* try_to_wake_up - wake up a thread
* @p: the to-be-woken-up thread
@@ -630,8 +610,9 @@ repeat_lock_task:
__activate_task(p, rq);
else {
activate_task(p, rq);
- if (task_preempts_curr(p, rq))
- resched_task(rq->curr);
+ if (TASK_PREEMPTS_CURR(p, rq) &&
+ (in_interrupt() || !p->mm))
+ resched_task(rq->curr);
}
success = 1;
}
@@ -685,7 +666,6 @@ void wake_up_forked_process(task_t * p)
p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
- p->waker = p->parent;
p->interactive_credit = 0;
p->prio = effective_prio(p);
@@ -1132,7 +1112,7 @@ static inline void pull_task(runqueue_t
* Note that idle threads have a prio of MAX_PRIO, for this test
* to be always true for them.
*/
- if (task_preempts_curr(p, this_rq))
+ if (TASK_PREEMPTS_CURR(p, this_rq))
set_need_resched();
}
_