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-rw-r--r--init/Kconfig23
1 files changed, 19 insertions, 4 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 6cfd71d06463..85c6870ed476 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -515,10 +515,25 @@ config RCU_BOOST_PRIO
depends on RCU_BOOST
default 1
help
- This option specifies the real-time priority to which preempted
- RCU readers are to be boosted. If you are working with CPU-bound
- real-time applications, you should specify a priority higher then
- the highest-priority CPU-bound application.
+ This option specifies the real-time priority to which long-term
+ preempted RCU readers are to be boosted. If you are working
+ with a real-time application that has one or more CPU-bound
+ threads running at a real-time priority level, you should set
+ RCU_BOOST_PRIO to a priority higher then the highest-priority
+ real-time CPU-bound thread. The default RCU_BOOST_PRIO value
+ of 1 is appropriate in the common case, which is real-time
+ applications that do not have any CPU-bound threads.
+
+ Some real-time applications might not have a single real-time
+ thread that saturates a given CPU, but instead might have
+ multiple real-time threads that, taken together, fully utilize
+ that CPU. In this case, you should set RCU_BOOST_PRIO to
+ a priority higher than the lowest-priority thread that is
+ conspiring to prevent the CPU from running any non-real-time
+ tasks. For example, if one thread at priority 10 and another
+ thread at priority 5 are between themselves fully consuming
+ the CPU time on a given CPU, then RCU_BOOST_PRIO should be
+ set to priority 6 or higher.
Specify the real-time priority, or take the default if unsure.