endmenu # "CPU/Task time and stats accounting"
-menu "RCU Subsystem"
-
-config TREE_RCU
- bool
- default y if !PREEMPT && SMP
- help
- This option selects the RCU implementation that is
- designed for very large SMP system with hundreds or
- thousands of CPUs. It also scales down nicely to
- smaller systems.
-
-config PREEMPT_RCU
- bool
- default y if PREEMPT
- help
- This option selects the RCU implementation that is
- designed for very large SMP systems with hundreds or
- thousands of CPUs, but for which real-time response
- is also required. It also scales down nicely to
- smaller systems.
-
- Select this option if you are unsure.
-
-config TINY_RCU
- bool
- default y if !PREEMPT && !SMP
- help
- This option selects the RCU implementation that is
- designed for UP systems from which real-time response
- is not required. This option greatly reduces the
- memory footprint of RCU.
-
-config RCU_EXPERT
- bool "Make expert-level adjustments to RCU configuration"
- default n
- help
- This option needs to be enabled if you wish to make
- expert-level adjustments to RCU configuration. By default,
- no such adjustments can be made, which has the often-beneficial
- side-effect of preventing "make oldconfig" from asking you all
- sorts of detailed questions about how you would like numerous
- obscure RCU options to be set up.
-
- Say Y if you need to make expert-level adjustments to RCU.
-
- Say N if you are unsure.
-
-config SRCU
- bool
- help
- This option selects the sleepable version of RCU. This version
- permits arbitrary sleeping or blocking within RCU read-side critical
- sections.
-
-config TINY_SRCU
- bool
- default y if SRCU && TINY_RCU
- help
- This option selects the single-CPU non-preemptible version of SRCU.
-
-config TREE_SRCU
- bool
- default y if SRCU && !TINY_RCU
- help
- This option selects the full-fledged version of SRCU.
-
-config TASKS_RCU
- bool
- default n
- select SRCU
- help
- This option enables a task-based RCU implementation that uses
- only voluntary context switch (not preemption!), idle, and
- user-mode execution as quiescent states.
-
-config RCU_STALL_COMMON
- def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
- help
- This option enables RCU CPU stall code that is common between
- the TINY and TREE variants of RCU. The purpose is to allow
- the tiny variants to disable RCU CPU stall warnings, while
- making these warnings mandatory for the tree variants.
-
-config RCU_NEED_SEGCBLIST
- def_bool ( TREE_RCU || PREEMPT_RCU || TREE_SRCU )
-
-config CONTEXT_TRACKING
- bool
-
-config CONTEXT_TRACKING_FORCE
- bool "Force context tracking"
- depends on CONTEXT_TRACKING
- default y if !NO_HZ_FULL
- help
- The major pre-requirement for full dynticks to work is to
- support the context tracking subsystem. But there are also
- other dependencies to provide in order to make the full
- dynticks working.
-
- This option stands for testing when an arch implements the
- context tracking backend but doesn't yet fullfill all the
- requirements to make the full dynticks feature working.
- Without the full dynticks, there is no way to test the support
- for context tracking and the subsystems that rely on it: RCU
- userspace extended quiescent state and tickless cputime
- accounting. This option copes with the absence of the full
- dynticks subsystem by forcing the context tracking on all
- CPUs in the system.
-
- Say Y only if you're working on the development of an
- architecture backend for the context tracking.
-
- Say N otherwise, this option brings an overhead that you
- don't want in production.
-
-
-config RCU_FANOUT
- int "Tree-based hierarchical RCU fanout value"
- range 2 64 if 64BIT
- range 2 32 if !64BIT
- depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
- default 64 if 64BIT
- default 32 if !64BIT
- 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 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.
-
-config RCU_FANOUT_LEAF
- int "Tree-based hierarchical RCU leaf-level fanout value"
- range 2 64 if 64BIT
- range 2 32 if !64BIT
- depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
- default 16
- help
- This option controls the leaf-level fanout of hierarchical
- implementations of RCU, and allows trading off cache misses
- against lock contention. Systems that synchronize their
- scheduling-clock interrupts for energy-efficiency reasons will
- want the default because the smaller leaf-level fanout keeps
- lock contention levels acceptably low. Very large systems
- (hundreds or thousands of CPUs) will instead want to set this
- value to the maximum value possible in order to reduce the
- number of cache misses incurred during RCU's grace-period
- initialization. These systems tend to run CPU-bound, and thus
- are not helped by synchronized interrupts, and thus tend to
- skew them, which reduces lock contention enough that large
- leaf-level fanouts work well. That said, setting leaf-level
- fanout to a large number will likely cause problematic
- lock contention on the leaf-level rcu_node structures unless
- you boot with the skew_tick kernel parameter.
-
- Select a specific number if testing RCU itself.
-
- Select the maximum permissible value for large systems, but
- please understand that you may also need to set the skew_tick
- kernel boot parameter to avoid contention on the rcu_node
- structure's locks.
-
- Take the default if unsure.
-
-config RCU_FAST_NO_HZ
- bool "Accelerate last non-dyntick-idle CPU's grace periods"
- depends on NO_HZ_COMMON && SMP && RCU_EXPERT
- default n
- help
- This option permits CPUs to enter dynticks-idle state even if
- they have RCU callbacks queued, and prevents RCU from waking
- these CPUs up more than roughly once every four jiffies (by
- default, you can adjust this using the rcutree.rcu_idle_gp_delay
- parameter), thus improving energy efficiency. On the other
- hand, this option increases the duration of RCU grace periods,
- for example, slowing down synchronize_rcu().
-
- Say Y if energy efficiency is critically important, and you
- don't care about increased grace-period durations.
-
- Say N if you are unsure.
-
-config RCU_BOOST
- bool "Enable RCU priority boosting"
- depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
- 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_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.
-
-config RCU_NOCB_CPU
- bool "Offload RCU callback processing from boot-selected CPUs"
- depends on TREE_RCU || PREEMPT_RCU
- depends on RCU_EXPERT || NO_HZ_FULL
- default n
- help
- Use this option to reduce OS jitter for aggressive HPC or
- real-time workloads. It can also be used to offload RCU
- callback invocation to energy-efficient CPUs in battery-powered
- asymmetric multiprocessors.
-
- This option offloads callback invocation from the set of
- CPUs specified at boot time by the rcu_nocbs parameter.
- For each such CPU, a kthread ("rcuox/N") will be created to
- invoke callbacks, where the "N" is the CPU being offloaded,
- and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
- "s" for RCU-sched. Nothing prevents this kthread from running
- on the specified CPUs, but (1) the kthreads may be preempted
- between each callback, and (2) affinity or cgroups can be used
- to force the kthreads to run on whatever set of CPUs is desired.
-
- Say Y here if you want to help to debug reduced OS jitter.
- Say N here if you are unsure.
-
-endmenu # "RCU Subsystem"
+source "kernel/rcu/Kconfig"
config BUILD_BIN2C
bool
--- /dev/null
+#
+# RCU-related configuration options
+#
+
+menu "RCU Subsystem"
+
+config TREE_RCU
+ bool
+ default y if !PREEMPT && SMP
+ help
+ This option selects the RCU implementation that is
+ designed for very large SMP system with hundreds or
+ thousands of CPUs. It also scales down nicely to
+ smaller systems.
+
+config PREEMPT_RCU
+ bool
+ default y if PREEMPT
+ help
+ This option selects the RCU implementation that is
+ designed for very large SMP systems with hundreds or
+ thousands of CPUs, but for which real-time response
+ is also required. It also scales down nicely to
+ smaller systems.
+
+ Select this option if you are unsure.
+
+config TINY_RCU
+ bool
+ default y if !PREEMPT && !SMP
+ help
+ This option selects the RCU implementation that is
+ designed for UP systems from which real-time response
+ is not required. This option greatly reduces the
+ memory footprint of RCU.
+
+config RCU_EXPERT
+ bool "Make expert-level adjustments to RCU configuration"
+ default n
+ help
+ This option needs to be enabled if you wish to make
+ expert-level adjustments to RCU configuration. By default,
+ no such adjustments can be made, which has the often-beneficial
+ side-effect of preventing "make oldconfig" from asking you all
+ sorts of detailed questions about how you would like numerous
+ obscure RCU options to be set up.
+
+ Say Y if you need to make expert-level adjustments to RCU.
+
+ Say N if you are unsure.
+
+config SRCU
+ bool
+ help
+ This option selects the sleepable version of RCU. This version
+ permits arbitrary sleeping or blocking within RCU read-side critical
+ sections.
+
+config TINY_SRCU
+ bool
+ default y if SRCU && TINY_RCU
+ help
+ This option selects the single-CPU non-preemptible version of SRCU.
+
+config TREE_SRCU
+ bool
+ default y if SRCU && !TINY_RCU
+ help
+ This option selects the full-fledged version of SRCU.
+
+config TASKS_RCU
+ bool
+ default n
+ select SRCU
+ help
+ This option enables a task-based RCU implementation that uses
+ only voluntary context switch (not preemption!), idle, and
+ user-mode execution as quiescent states.
+
+config RCU_STALL_COMMON
+ def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
+ help
+ This option enables RCU CPU stall code that is common between
+ the TINY and TREE variants of RCU. The purpose is to allow
+ the tiny variants to disable RCU CPU stall warnings, while
+ making these warnings mandatory for the tree variants.
+
+config RCU_NEED_SEGCBLIST
+ def_bool ( TREE_RCU || PREEMPT_RCU || TREE_SRCU )
+
+config CONTEXT_TRACKING
+ bool
+
+config CONTEXT_TRACKING_FORCE
+ bool "Force context tracking"
+ depends on CONTEXT_TRACKING
+ default y if !NO_HZ_FULL
+ help
+ The major pre-requirement for full dynticks to work is to
+ support the context tracking subsystem. But there are also
+ other dependencies to provide in order to make the full
+ dynticks working.
+
+ This option stands for testing when an arch implements the
+ context tracking backend but doesn't yet fullfill all the
+ requirements to make the full dynticks feature working.
+ Without the full dynticks, there is no way to test the support
+ for context tracking and the subsystems that rely on it: RCU
+ userspace extended quiescent state and tickless cputime
+ accounting. This option copes with the absence of the full
+ dynticks subsystem by forcing the context tracking on all
+ CPUs in the system.
+
+ Say Y only if you're working on the development of an
+ architecture backend for the context tracking.
+
+ Say N otherwise, this option brings an overhead that you
+ don't want in production.
+
+
+config RCU_FANOUT
+ int "Tree-based hierarchical RCU fanout value"
+ range 2 64 if 64BIT
+ range 2 32 if !64BIT
+ depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
+ default 64 if 64BIT
+ default 32 if !64BIT
+ 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 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.
+
+config RCU_FANOUT_LEAF
+ int "Tree-based hierarchical RCU leaf-level fanout value"
+ range 2 64 if 64BIT
+ range 2 32 if !64BIT
+ depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
+ default 16
+ help
+ This option controls the leaf-level fanout of hierarchical
+ implementations of RCU, and allows trading off cache misses
+ against lock contention. Systems that synchronize their
+ scheduling-clock interrupts for energy-efficiency reasons will
+ want the default because the smaller leaf-level fanout keeps
+ lock contention levels acceptably low. Very large systems
+ (hundreds or thousands of CPUs) will instead want to set this
+ value to the maximum value possible in order to reduce the
+ number of cache misses incurred during RCU's grace-period
+ initialization. These systems tend to run CPU-bound, and thus
+ are not helped by synchronized interrupts, and thus tend to
+ skew them, which reduces lock contention enough that large
+ leaf-level fanouts work well. That said, setting leaf-level
+ fanout to a large number will likely cause problematic
+ lock contention on the leaf-level rcu_node structures unless
+ you boot with the skew_tick kernel parameter.
+
+ Select a specific number if testing RCU itself.
+
+ Select the maximum permissible value for large systems, but
+ please understand that you may also need to set the skew_tick
+ kernel boot parameter to avoid contention on the rcu_node
+ structure's locks.
+
+ Take the default if unsure.
+
+config RCU_FAST_NO_HZ
+ bool "Accelerate last non-dyntick-idle CPU's grace periods"
+ depends on NO_HZ_COMMON && SMP && RCU_EXPERT
+ default n
+ help
+ This option permits CPUs to enter dynticks-idle state even if
+ they have RCU callbacks queued, and prevents RCU from waking
+ these CPUs up more than roughly once every four jiffies (by
+ default, you can adjust this using the rcutree.rcu_idle_gp_delay
+ parameter), thus improving energy efficiency. On the other
+ hand, this option increases the duration of RCU grace periods,
+ for example, slowing down synchronize_rcu().
+
+ Say Y if energy efficiency is critically important, and you
+ don't care about increased grace-period durations.
+
+ Say N if you are unsure.
+
+config RCU_BOOST
+ bool "Enable RCU priority boosting"
+ depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
+ 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_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.
+
+config RCU_NOCB_CPU
+ bool "Offload RCU callback processing from boot-selected CPUs"
+ depends on TREE_RCU || PREEMPT_RCU
+ depends on RCU_EXPERT || NO_HZ_FULL
+ default n
+ help
+ Use this option to reduce OS jitter for aggressive HPC or
+ real-time workloads. It can also be used to offload RCU
+ callback invocation to energy-efficient CPUs in battery-powered
+ asymmetric multiprocessors.
+
+ This option offloads callback invocation from the set of
+ CPUs specified at boot time by the rcu_nocbs parameter.
+ For each such CPU, a kthread ("rcuox/N") will be created to
+ invoke callbacks, where the "N" is the CPU being offloaded,
+ and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
+ "s" for RCU-sched. Nothing prevents this kthread from running
+ on the specified CPUs, but (1) the kthreads may be preempted
+ between each callback, and (2) affinity or cgroups can be used
+ to force the kthreads to run on whatever set of CPUs is desired.
+
+ Say Y here if you want to help to debug reduced OS jitter.
+ Say N here if you are unsure.
+
+endmenu # "RCU Subsystem"
projects / linux-2.6-block.git / commitdiff