* Satoru Takeuchi <[EMAIL PROTECTED]> wrote:
> Hi Ingo and all,
>
> When I was executing massive interactive processes, I found that some
> of them occupy CPU time and the others hardly run.
yeah.
> I also attach the test program which easily recreates this problem.
thanks, this is really helpful - does the patch below improve the
situation?
Ingo
---------------------->
Subject: [patch] sched: improve starvation prevention
From: Ingo Molnar <[EMAIL PROTECTED]>
improve starvation prevention by guaranteeing STARVATION_LIMIT. This
also simplifies the code a bit.
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
kernel/sched.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
Index: linux/kernel/sched.c
===================================================================
--- linux.orig/kernel/sched.c
+++ linux/kernel/sched.c
@@ -235,7 +235,7 @@ struct rq {
*/
unsigned long nr_uninterruptible;
- unsigned long expired_timestamp;
+ unsigned long switch_timestamp;
/* Cached timestamp set by update_cpu_clock() */
unsigned long long most_recent_timestamp;
struct task_struct *curr, *idle;
@@ -3103,9 +3103,9 @@ static inline int expired_starving(struc
{
if (rq->curr->static_prio > rq->best_expired_prio)
return 1;
- if (!STARVATION_LIMIT || !rq->expired_timestamp)
+ if (!STARVATION_LIMIT)
return 0;
- if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running)
+ if (jiffies - rq->switch_timestamp > STARVATION_LIMIT)
return 1;
return 0;
}
@@ -3218,8 +3218,6 @@ static void task_running_tick(struct rq
p->time_slice = task_timeslice(p);
p->first_time_slice = 0;
- if (!rq->expired_timestamp)
- rq->expired_timestamp = jiffies;
if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {
enqueue_task(p, rq->expired);
if (p->static_prio < rq->best_expired_prio)
@@ -3406,7 +3404,7 @@ need_resched_nonpreemptible:
idle_balance(cpu, rq);
if (!rq->nr_running) {
next = rq->idle;
- rq->expired_timestamp = 0;
+ rq->switch_timestamp = jiffies;
goto switch_tasks;
}
}
@@ -3420,7 +3418,7 @@ need_resched_nonpreemptible:
rq->active = rq->expired;
rq->expired = array;
array = rq->active;
- rq->expired_timestamp = 0;
+ rq->switch_timestamp = jiffies;
rq->best_expired_prio = MAX_PRIO;
}
-
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