Messages in this thread Patch in this message | | | Date | Mon, 30 Nov 2009 11:13:07 -0800 | From | Mandeep Singh Baines <> | Subject | Re: PATCH: softlockup: Fix hung_task_check_count sysctl |
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To disable hung_task at runtime:
# echo 0 > /proc/sys/kernel/hung_task_check_count
33 /* 34 * Zero means infinite timeout - no checking done: 35 */ 36 unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
For hung_task_check_count, 0 means there is no maximum so all tasks are checked.
Anton Blanchard (anton@samba.org) wrote: > > I'm seeing spikes of up to 0.5ms in khungtaskd on a large machine. To reduce > this source of jitter I tried setting hung_task_check_count to 0: >
Hmm, maybe khungtaskd should be run using SCHED_IDLE.
> # echo 0 > /proc/sys/kernel/hung_task_check_count > > which didn't have the intended response. Change to a post increment of > max_count, so a value of 0 means check 0 tasks. > > Signed-off-by: Anton Blanchard <anton@samba.org> > --- > > Index: linux.trees.git/kernel/hung_task.c > =================================================================== > --- linux.trees.git.orig/kernel/hung_task.c 2009-11-27 13:11:46.000000000 +1100 > +++ linux.trees.git/kernel/hung_task.c 2009-11-27 13:11:57.000000000 +1100 > @@ -144,7 +144,7 @@ static void check_hung_uninterruptible_t > > rcu_read_lock(); > do_each_thread(g, t) { > - if (!--max_count) > + if (!max_count--) > goto unlock; > if (!--batch_count) { > batch_count = HUNG_TASK_BATCHING;
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