Commit 0500873d authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

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: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
parent 3545832f

Documentation/RCU/stallwarn.txt

+6 −0
Original line number Original line Diff line number Diff line
@@ -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

	CONFIG_PREEMPT_RCU case, you might see stall-warning

	messages.

	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

o	A periodic interrupt whose handler takes longer than the time

	interval between successive pairs of interrupts.  This can

	interval between successive pairs of interrupts.  This can

	prevent RCU's kthreads and softirq handlers from running.

	prevent RCU's kthreads and softirq handlers from running.