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authorPaul E. McKenney <paulmck@linux.ibm.com>2019-07-08 08:01:50 -0700
committerPaul E. McKenney <paulmck@linux.ibm.com>2019-08-01 14:07:41 -0700
commit0500873de968df6fdef5752d7bbdca317ddc220b (patch)
treee0d627a5c71019afb30a58959f8d64903f0e5b6f /Documentation/RCU
parent3545832fc22e2316d9c289f6ba825710a268bfa6 (diff)
doc: Add rcutree.kthread_prio pointer to stallwarn.txt
This commit adds mention of the rcutree.kthread_prio kernel boot parameter to the discussion of how high-priority real-time tasks can result in RCU CPU stall warnings. (However, this does not necessarily help when the high-priority real-time tasks are using dubious deadlines.) Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/stallwarn.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index 13e88fc00f01..f48f4621ccbc 100644
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -57,6 +57,12 @@ o A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that
CONFIG_PREEMPT_RCU case, you might see stall-warning
messages.
+ You can use the rcutree.kthread_prio kernel boot parameter to
+ increase the scheduling priority of RCU's kthreads, which can
+ help avoid this problem. However, please note that doing this
+ can increase your system's context-switch rate and thus degrade
+ performance.
+
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.