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SubjectPATCH: softlockup: Fix hung_task_check_count sysctl

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:

# 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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