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> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: msb@google.com LKML-Reference: <20091127022820.GU32182@kryten> Signed-off-by: Ingo Molnar <mingo@elte.hu>

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> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: msb@google.com LKML-Reference: <20091127022820.GU32182@kryten> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Anton Blanchard · Ingo Molnar
1 parent a8a8a669ea
Showing 1 changed file with 1 additions and 1 deletions Side-by-side Diff
kernel/hung_task.c
@@ -144,7 +144,7 @@
  
 	rcu_read_lock();
 	do_each_thread(g, t) {
-		if (!--max_count)
+		if (!max_count--)
 			goto unlock;
 		if (!--batch_count) {
 			batch_count = HUNG_TASK_BATCHING;
...	...	@@ -144,7 +144,7 @@
144	144
145	145	rcu_read_lock();
146	146	do_each_thread(g, t) {
147		- if (!--max_count)
	147	+ if (!max_count--)
148	148	goto unlock;
149	149	if (!--batch_count) {
150	150	batch_count = HUNG_TASK_BATCHING;