| From | "Paul E. McKenney" <> | Subject | [PATCH RFC tip/core/rcu 09/28] rcu: Document failing tick as cause of RCU CPU stall warning | Date | Wed, 2 Nov 2011 13:30:30 -0700 |
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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> --- Documentation/RCU/stallwarn.txt | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 4e95920..f3e0625 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 -- 1.7.3.2
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