|author||Paul E. McKenney <firstname.lastname@example.org>||2014-12-17 08:35:02 -0800|
|committer||Paul E. McKenney <email@example.com>||2015-01-15 23:33:15 -0800|
rcu: Add GP-kthread-starvation checks to CPU stall warnings
This commit adds a message that is printed if the relevant grace-period kthread has not been able to run for the two seconds preceding the stall warning. (The two seconds is double the maximum interval between successive bouts of quiescent-state forcing.) Signed-off-by: Paul E. McKenney <firstname.lastname@example.org>
Diffstat (limited to 'Documentation/RCU')
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index 55f9707fe60a..53e7d2856db6 100644
@@ -152,6 +152,15 @@ no non-lazy callbacks ("." is printed otherwise, as shown above) and
"D" indicates that dyntick-idle processing is enabled ("." is printed
otherwise, for example, if disabled via the "nohz=" kernel boot parameter).
+If the relevant grace-period kthread has been unable to run prior to
+the stall warning, the following additional line is printed:
+ rcu_preempt kthread starved for 2023 jiffies!
+Starving the grace-period kthreads of CPU time can of course result in
+RCU CPU stall warnings even when all CPUs and tasks have passed through
+the required quiescent states.
Multiple Warnings From One Stall