Commit 2c01531f authored Oct 02, 2011 by Paul E. McKenney

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>

parent 91afaf30

Documentation/RCU/stallwarn.txt

+5 −0

Original line number	Diff line number	Diff line
		@@ -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