lkml.org 
[lkml]   [2013]   [May]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 2/3] nohz: Disable LOCKUP_DETECTOR when NO_HZ_FULL is enabled
Trying to test the nohz_full code, I was not able to get it to work.
Finally I enabled the tick_stop tracepoint and it showed:

tick_stop: success=no msg=perf events running

I talked to Frederic Weisbecker about this and he informed me that
perf is used by the lockup detector. I checked the code, and sure
enough it is.

As perf is always running when LOCKUP_DETECTOR is enabled, which
will always disable nohz_full from working, instead of confusing
users, disable LOCKUP_DETECTOR when NO_HZ_FULL is enabled.

When perf is changed such that it does not prevent nohz_full from
working, then we can and should remove this constraint.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 566cf2b..1364d09 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -174,6 +174,8 @@ config DEBUG_SHIRQ
config LOCKUP_DETECTOR
bool "Detect Hard and Soft Lockups"
depends on DEBUG_KERNEL && !S390
+ # Lockup detector currently prevents NO_HZ_FULL from working
+ depends on !NO_HZ_FULL
help
Say Y here to enable the kernel to act as a watchdog to detect
hard and soft lockups.


\
 
 \ /
  Last update: 2013-05-10 23:21    [W:0.088 / U:0.892 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site