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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-10-02 17:21:18 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-12-11 10:31:26 -0800
commit2c01531f08f8ba663a20d8472a3032f6df133b6e (patch)
tree3a6c5ce1fc95258e5431968a0011f6e80f3c431e /Documentation/RCU
parent91afaf300269aa99a4d646969b3258b74294ac4d (diff)
downloadlinux-2c01531f08f8ba663a20d8472a3032f6df133b6e.tar.gz
rcu: Document failing tick as cause of RCU CPU stall warning
One of lclaudio's systems was seeing RCU CPU stall warnings from idle. These turned out to be caused by a bug that stopped scheduling-clock tick interrupts from being sent to a given CPU for several hundred seconds. This commit therefore updates the documentation to call this out as a possible cause for RCU CPU stall warnings. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/stallwarn.txt5
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index 4e959208f73..f3e0625f429 100644
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -101,6 +101,11 @@ o A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that
CONFIG_TREE_PREEMPT_RCU case, you might see stall-warning
messages.
+o A hardware or software issue shuts off the scheduler-clock
+ interrupt on a CPU that is not in dyntick-idle mode. This
+ problem really has happened, and seems to be most likely to
+ result in RCU CPU stall warnings for CONFIG_NO_HZ=n kernels.
+
o A bug in the RCU implementation.
o A hardware failure. This is quite unlikely, but has occurred