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| -rw-r--r-- | Documentation/RCU/stallwarn.txt | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 96a3d81837e1..21b8913acbdf 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -40,7 +40,9 @@ o Booting Linux using a console connection that is too slow to o Anything that prevents RCU's grace-period kthreads from running. This can result in the "All QSes seen" console-log message. This message will include information on when the kthread last - ran and how often it should be expected to run. + ran and how often it should be expected to run. It can also + result in the "rcu_.*kthread starved for" console-log message, + which will include additional debugging information. o A CPU-bound real-time task in a CONFIG_PREEMPT kernel, which might happen to preempt a low-priority task in the middle of an RCU @@ -60,6 +62,14 @@ o A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that CONFIG_PREEMPT_RCU case, you might see stall-warning messages. +o A periodic interrupt whose handler takes longer than the time + interval between successive pairs of interrupts. This can + prevent RCU's kthreads and softirq handlers from running. + Note that certain high-overhead debugging options, for example + the function_graph tracer, can result in interrupt handler taking + considerably longer than normal, which can in turn result in + RCU CPU stall warnings. + 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 |