lkml.org 
[lkml]   [2006]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 2/2] sched_exit: move the callsite to do_exit()
sched_exit() is called by release_task(). If the task auto-reaps itself
this call happens a bit too early (the task still uses cpu after that).
If the task goes to TASK_ZOMBIE this call is unpredictably delayed.

I think it is better to do sched_exit() right before the last schedule().

We can use read_lock_rcu() instead of write_lock(tasklist). In that case
it is possible that sched_exit() changes ->time_slice/->sleep_avg of the
already dead ->parent, but I think this is tolerable.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- 2.6.17-rc6/kernel/sched.c~MOVE 2006-06-23 04:48:48.000000000 +0400
+++ 2.6.17-rc6/kernel/sched.c 2006-06-23 06:46:57.000000000 +0400
@@ -1479,10 +1479,13 @@ void fastcall wake_up_new_task(task_t *p
*/
void fastcall sched_exit(task_t *p)
{
- task_t *parent = p->parent;
+ task_t *parent;
unsigned long flags;
runqueue_t *rq;

+ rcu_read_lock();
+ parent = p->real_parent;
+
/*
* If the child was a (relative-) CPU hog then decrease
* the sleep_avg of the parent as well.
@@ -1498,6 +1501,7 @@ void fastcall sched_exit(task_t *p)
(EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
(EXIT_WEIGHT + 1);
task_rq_unlock(rq, &flags);
+ rcu_read_unlock();
}

/**
--- 2.6.17-rc6/kernel/exit.c~MOVE 2006-06-18 06:10:26.000000000 +0400
+++ 2.6.17-rc6/kernel/exit.c 2006-06-23 05:45:42.000000000 +0400
@@ -170,7 +170,6 @@ repeat:
zap_leader = (leader->exit_signal == -1);
}

- sched_exit(p);
write_unlock_irq(&tasklist_lock);
spin_unlock(&p->proc_lock);
proc_pid_flush(proc_dentry);
@@ -940,6 +939,8 @@ fastcall NORET_TYPE void do_exit(long co
if (tsk->splice_pipe)
__free_pipe_info(tsk->splice_pipe);

+ sched_exit(tsk);
+
/* PF_DEAD causes final put_task_struct after we schedule. */
preempt_disable();
BUG_ON(tsk->flags & PF_DEAD);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-06-23 01:20    [W:1.490 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site