|author||Paul E. McKenney <firstname.lastname@example.org>||2011-10-02 17:21:18 -0700|
|committer||Paul E. McKenney <email@example.com>||2011-12-11 10:31:26 -0800|
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 <firstname.lastname@example.org> Reviewed-by: Josh Triplett <email@example.com>
Diffstat (limited to 'Documentation/RCU')
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index 4e959208f73..f3e0625f429 100644
@@ -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
+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