rcu: move Kconfig menu
Move RCU Kconfig options from top-level menu to an "RCU Subsystem" menu under the "General Setup" menu. Signed-off-by: Mike Travis <travis@sgi.com> Tested-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mike Travis
Ingo Molnar
parent
baf48f6577
commit
c903ff8379
179
init/Kconfig
179
init/Kconfig
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@ -238,6 +238,98 @@ config AUDIT_TREE
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def_bool y
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depends on AUDITSYSCALL && INOTIFY
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menu "RCU Subsystem"
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choice
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prompt "RCU Implementation"
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default CLASSIC_RCU
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config CLASSIC_RCU
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bool "Classic RCU"
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help
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This option selects the classic RCU implementation that is
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designed for best read-side performance on non-realtime
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systems.
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Select this option if you are unsure.
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config TREE_RCU
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bool "Tree-based hierarchical RCU"
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help
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This option selects the RCU implementation that is
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designed for very large SMP system with hundreds or
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thousands of CPUs.
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config PREEMPT_RCU
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bool "Preemptible RCU"
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depends on PREEMPT
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help
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This option reduces the latency of the kernel by making certain
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RCU sections preemptible. Normally RCU code is non-preemptible, if
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this option is selected then read-only RCU sections become
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preemptible. This helps latency, but may expose bugs due to
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now-naive assumptions about each RCU read-side critical section
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remaining on a given CPU through its execution.
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endchoice
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config RCU_TRACE
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bool "Enable tracing for RCU"
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depends on TREE_RCU || PREEMPT_RCU
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help
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This option provides tracing in RCU which presents stats
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in debugfs for debugging RCU implementation.
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Say Y here if you want to enable RCU tracing
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Say N if you are unsure.
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config RCU_FANOUT
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int "Tree-based hierarchical RCU fanout value"
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range 2 64 if 64BIT
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range 2 32 if !64BIT
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depends on TREE_RCU
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default 64 if 64BIT
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default 32 if !64BIT
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help
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This option controls the fanout of hierarchical implementations
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of RCU, allowing RCU to work efficiently on machines with
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large numbers of CPUs. This value must be at least the cube
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root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
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systems and up to 262,144 for 64-bit systems.
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Select a specific number if testing RCU itself.
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Take the default if unsure.
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config RCU_FANOUT_EXACT
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bool "Disable tree-based hierarchical RCU auto-balancing"
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depends on TREE_RCU
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default n
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help
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This option forces use of the exact RCU_FANOUT value specified,
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regardless of imbalances in the hierarchy. This is useful for
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testing RCU itself, and might one day be useful on systems with
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strong NUMA behavior.
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Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
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Say N if unsure.
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config TREE_RCU_TRACE
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def_bool RCU_TRACE && TREE_RCU
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select DEBUG_FS
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help
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This option provides tracing for the TREE_RCU implementation,
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permitting Makefile to trivially select kernel/rcutree_trace.c.
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config PREEMPT_RCU_TRACE
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def_bool RCU_TRACE && PREEMPT_RCU
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select DEBUG_FS
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help
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This option provides tracing for the PREEMPT_RCU implementation,
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permitting Makefile to trivially select kernel/rcupreempt_trace.c.
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endmenu # "RCU Subsystem"
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config IKCONFIG
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tristate "Kernel .config support"
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---help---
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@ -973,90 +1065,3 @@ source "block/Kconfig"
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config PREEMPT_NOTIFIERS
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bool
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choice
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prompt "RCU Implementation"
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default CLASSIC_RCU
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config CLASSIC_RCU
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bool "Classic RCU"
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help
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This option selects the classic RCU implementation that is
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designed for best read-side performance on non-realtime
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systems.
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Select this option if you are unsure.
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config TREE_RCU
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bool "Tree-based hierarchical RCU"
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help
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This option selects the RCU implementation that is
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designed for very large SMP system with hundreds or
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thousands of CPUs.
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config PREEMPT_RCU
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bool "Preemptible RCU"
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depends on PREEMPT
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help
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This option reduces the latency of the kernel by making certain
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RCU sections preemptible. Normally RCU code is non-preemptible, if
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this option is selected then read-only RCU sections become
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preemptible. This helps latency, but may expose bugs due to
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now-naive assumptions about each RCU read-side critical section
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remaining on a given CPU through its execution.
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endchoice
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config RCU_TRACE
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bool "Enable tracing for RCU"
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depends on TREE_RCU || PREEMPT_RCU
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help
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This option provides tracing in RCU which presents stats
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in debugfs for debugging RCU implementation.
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Say Y here if you want to enable RCU tracing
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Say N if you are unsure.
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config RCU_FANOUT
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int "Tree-based hierarchical RCU fanout value"
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range 2 64 if 64BIT
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range 2 32 if !64BIT
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depends on TREE_RCU
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default 64 if 64BIT
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default 32 if !64BIT
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help
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This option controls the fanout of hierarchical implementations
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of RCU, allowing RCU to work efficiently on machines with
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large numbers of CPUs. This value must be at least the cube
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root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
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systems and up to 262,144 for 64-bit systems.
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Select a specific number if testing RCU itself.
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Take the default if unsure.
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config RCU_FANOUT_EXACT
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bool "Disable tree-based hierarchical RCU auto-balancing"
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depends on TREE_RCU
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default n
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help
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This option forces use of the exact RCU_FANOUT value specified,
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regardless of imbalances in the hierarchy. This is useful for
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testing RCU itself, and might one day be useful on systems with
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strong NUMA behavior.
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Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
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Say N if unsure.
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config TREE_RCU_TRACE
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def_bool RCU_TRACE && TREE_RCU
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select DEBUG_FS
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help
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This option provides tracing for the TREE_RCU implementation,
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permitting Makefile to trivially select kernel/rcutree_trace.c.
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config PREEMPT_RCU_TRACE
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def_bool RCU_TRACE && PREEMPT_RCU
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select DEBUG_FS
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help
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This option provides tracing for the PREEMPT_RCU implementation,
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permitting Makefile to trivially select kernel/rcupreempt_trace.c.
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