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authorPaul E. McKenney <paul.mckenney@linaro.org>2010-09-27 17:25:23 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-11-29 22:01:54 -0800
commit24278d148316d2180be6df40e06db013d8b232b8 (patch)
tree6a579d483f8f799b352e39b972a7e03cc6204fc1 /init
parentb2c0710c464ede15e1fc52fb1e7ee9ba54cea186 (diff)
downloadlinux-2.6.38-lt-ux500-24278d148316d2180be6df40e06db013d8b232b8.tar.gz
rcu: priority boosting for TINY_PREEMPT_RCU
Add priority boosting, but only for TINY_PREEMPT_RCU. This is enabled by the default-off RCU_BOOST kernel parameter. The priority to which to boost preempted RCU readers is controlled by the RCU_BOOST_PRIO kernel parameter (defaulting to real-time priority 1) and the time to wait before boosting the readers blocking a given grace period is controlled by the RCU_BOOST_DELAY kernel parameter (defaulting to 500 milliseconds). Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig39
1 files changed, 39 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig
index a619a1ac7f4..48efefcac12 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -450,6 +450,45 @@ config TREE_RCU_TRACE
TREE_PREEMPT_RCU implementations, permitting Makefile to
trivially select kernel/rcutree_trace.c.
+config RCU_BOOST
+ bool "Enable RCU priority boosting"
+ depends on RT_MUTEXES && TINY_PREEMPT_RCU
+ default n
+ help
+ This option boosts the priority of preempted RCU readers that
+ block the current preemptible RCU grace period for too long.
+ This option also prevents heavy loads from blocking RCU
+ callback invocation for all flavors of RCU.
+
+ Say Y here if you are working with real-time apps or heavy loads
+ Say N here if you are unsure.
+
+config RCU_BOOST_PRIO
+ int "Real-time priority to boost RCU readers to"
+ range 1 99
+ 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.
+
+ Specify the real-time priority, or take the default if unsure.
+
+config RCU_BOOST_DELAY
+ int "Milliseconds to delay boosting after RCU grace-period start"
+ range 0 3000
+ depends on RCU_BOOST
+ default 500
+ help
+ This option specifies the time to wait after the beginning of
+ a given grace period before priority-boosting preempted RCU
+ readers blocking that grace period. Note that any RCU reader
+ blocking an expedited RCU grace period is boosted immediately.
+
+ Accept the default if unsure.
+
endmenu # "RCU Subsystem"
config IKCONFIG