path: root/Documentation/RCU
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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-12-17 08:35:02 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-01-15 23:33:15 -0800
commitfb81a44b88e6173ed0f6e9d6a1afa5305fb63f6e (patch)
treefaa68798164b89dd6d37a9a591e62e9dfc7afdad /Documentation/RCU
parent5cd37193ce8539be1e6ef76be226f4bcc984e0f5 (diff)
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 <paulmck@linux.vnet.ibm.com>
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
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -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

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