rcu: add tracing for TINY_RCU and TINY_PREEMPT_RCU

[deliverable/linux.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index 2de5b1cbadd9e47138f879d23cc4d2d5066d32d7..929adf6cb6b4ac8aa0151ff868ae0f8d128edd0a 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -340,6 +340,7 @@ choice
 
 config TREE_RCU
        bool "Tree-based hierarchical RCU"
+       depends on !PREEMPT && SMP
        help
          This option selects the RCU implementation that is
          designed for very large SMP system with hundreds or
@@ -347,7 +348,7 @@ config TREE_RCU
          smaller systems.
 
 config TREE_PREEMPT_RCU
-       bool "Preemptable tree-based hierarchical RCU"
+       bool "Preemptible tree-based hierarchical RCU"
        depends on PREEMPT
        help
          This option selects the RCU implementation that is
@@ -365,11 +366,24 @@ config TINY_RCU
          is not required.  This option greatly reduces the
          memory footprint of RCU.
 
+config TINY_PREEMPT_RCU
+       bool "Preemptible UP-only small-memory-footprint RCU"
+       depends on !SMP && PREEMPT
+       help
+         This option selects the RCU implementation that is designed
+         for real-time UP systems.  This option greatly reduces the
+         memory footprint of RCU.
+
 endchoice
 
+config PREEMPT_RCU
+       def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
+       help
+         This option enables preemptible-RCU code that is common between
+         the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
+
 config RCU_TRACE
        bool "Enable tracing for RCU"
-       depends on TREE_RCU || TREE_PREEMPT_RCU
        help
          This option provides tracing in RCU which presents stats
          in debugfs for debugging RCU implementation.
@@ -387,9 +401,12 @@ config RCU_FANOUT
        help
          This option controls the fanout of hierarchical implementations
          of RCU, allowing RCU to work efficiently on machines with
-         large numbers of CPUs.  This value must be at least the cube
-         root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
-         systems and up to 262,144 for 64-bit systems.
+         large numbers of CPUs.  This value must be at least the fourth
+         root of NR_CPUS, which allows NR_CPUS to be insanely large.
+         The default value of RCU_FANOUT should be used for production
+         systems, but if you are stress-testing the RCU implementation
+         itself, small RCU_FANOUT values allow you to test large-system
+         code paths on small(er) systems.
 
          Select a specific number if testing RCU itself.
          Take the default if unsure.
@@ -432,6 +449,45 @@ 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