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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-10-02 17:21:18 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-12-11 10:31:26 -0800 |
| commit | 2c01531f08f8ba663a20d8472a3032f6df133b6e (patch) | |
| tree | 3a6c5ce1fc95258e5431968a0011f6e80f3c431e | |
| parent | 91afaf300269aa99a4d646969b3258b74294ac4d (diff) | |
| download | lwn-2c01531f08f8ba663a20d8472a3032f6df133b6e.tar.gz lwn-2c01531f08f8ba663a20d8472a3032f6df133b6e.zip | |
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>
| -rw-r--r-- | 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 4e959208f736..f3e0625f4290 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 |