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"
 
 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
        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
          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
        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.
 
          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
 
 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"
 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.
        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
        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.
 
          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.
 
          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
 endmenu # "RCU Subsystem"
 
 config IKCONFIG