path: root/init/Kconfig
diff options
authorRusty Russell <rusty@rustcorp.com.au>2008-12-31 23:05:57 +1030
committerRusty Russell <rusty@rustcorp.com.au>2008-12-31 23:05:57 +1030
commit2ca1a615835d9f4990f42102ab1f2ef434e7e89c (patch)
tree726cf3d5f29a6c66c44e4bd68e7ebed2fd83d059 /init/Kconfig
parente12f0102ac81d660c9f801d0a0e10ccf4537a9de (diff)
parent6a94cb73064c952255336cc57731904174b2c58f (diff)
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts: arch/x86/kernel/io_apic.c
Diffstat (limited to 'init/Kconfig')
1 files changed, 83 insertions, 3 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 8e9904fc302..f6281711166 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -945,10 +945,90 @@ source "block/Kconfig"
+ prompt "RCU Implementation"
+ default CLASSIC_RCU
- def_bool !PREEMPT_RCU
+ bool "Classic RCU"
This option selects the classic RCU implementation that is
designed for best read-side performance on non-realtime
- systems. Classic RCU is the default. Note that the
- PREEMPT_RCU symbol is used to select/deselect this option.
+ systems.
+ Select this option if you are unsure.
+config TREE_RCU
+ bool "Tree-based hierarchical RCU"
+ help
+ This option selects the RCU implementation that is
+ designed for very large SMP system with hundreds or
+ thousands of CPUs.
+ bool "Preemptible RCU"
+ depends on PREEMPT
+ help
+ This option reduces the latency of the kernel by making certain
+ RCU sections preemptible. Normally RCU code is non-preemptible, if
+ this option is selected then read-only RCU sections become
+ preemptible. This helps latency, but may expose bugs due to
+ now-naive assumptions about each RCU read-side critical section
+ remaining on a given CPU through its execution.
+config RCU_TRACE
+ bool "Enable tracing for RCU"
+ depends on TREE_RCU || PREEMPT_RCU
+ help
+ This option provides tracing in RCU which presents stats
+ in debugfs for debugging RCU implementation.
+ Say Y here if you want to enable RCU tracing
+ Say N if you are unsure.
+config RCU_FANOUT
+ int "Tree-based hierarchical RCU fanout value"
+ range 2 64 if 64BIT
+ range 2 32 if !64BIT
+ depends on TREE_RCU
+ 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 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.
+ Select a specific number if testing RCU itself.
+ Take the default if unsure.
+ bool "Disable tree-based hierarchical RCU auto-balancing"
+ depends on TREE_RCU
+ default n
+ help
+ This option forces use of the exact RCU_FANOUT value specified,
+ regardless of imbalances in the hierarchy. This is useful for
+ testing RCU itself, and might one day be useful on systems with
+ strong NUMA behavior.
+ Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
+ Say N if unsure.
+ def_bool RCU_TRACE && TREE_RCU
+ select DEBUG_FS
+ help
+ This option provides tracing for the TREE_RCU implementation,
+ permitting Makefile to trivially select kernel/rcutree_trace.c.
+ select DEBUG_FS
+ help
+ This option provides tracing for the PREEMPT_RCU implementation,
+ permitting Makefile to trivially select kernel/rcupreempt_trace.c.