Messages in this thread Patch in this message | | | Date | Fri, 23 Jan 2009 18:56:18 -0800 | From | Mandeep Singh Baines <> | Subject | Re: [PATCH v3] softlockup: remove hung_task_check_count |
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Ingo Molnar (mingo@elte.hu) wrote: > > not sure i like the whole idea of removing the max iterations check. In > theory if there's a _ton_ of tasks, we could spend a lot of time looping > there. So it always looked prudent to limit it somewhat. >
We could go back to exporting max iterations to proc, and set the nice value higher.
Or:
Instead of searching the tasklist from the beginning every time, continue where you left off. On loaded systems, will take a while to search the entire list but at least all tasks will be checked.
Something like this:
diff --git a/kernel/hung_task.c b/kernel/hung_task.c index ba8ccd4..d220796 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -109,6 +109,15 @@ static void check_hung_task(struct task_struct *t, unsigned long now, panic("hung_task: blocked tasks"); } +static void wait_till_next_iteration(struct task_struct *t) +{ + get_task_state(t); + read_unlock(&tasklist_lock); + schedule_timeout_interruptible(hung_task_poll_jiffies); + read_lock(&tasklist_lock); + put_task_state(t); +} + /* * Check whether a TASK_UNINTERRUPTIBLE does not get woken up for * a really long time (120 seconds). If that happens, print out @@ -129,8 +138,14 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) read_lock(&tasklist_lock); do_each_thread(g, t) { - if (!--max_count) - goto unlock; + if (!--max_count) { + max_count = HUNG_TASK_CHECK_COUNT; + wait_till_next_iteration(t); + timeout = sysctl_hung_task_timeout_secs; + /* Exit loop if t was unlinked or timeout set to 0. */ + if (!timeout || t->state == TASK_DEAD) + goto unlock; + } /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */ if (t->state == TASK_UNINTERRUPTIBLE) check_hung_task(t, now, timeout);
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