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authorLinus Torvalds <torvalds@linux-foundation.org>2010-10-21 12:54:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-21 12:54:12 -0700
commit888a6f77e0418b049f83d37547c209b904d30af4 (patch)
tree42cdb9f781d2177e6b380e69a66a27ec7705f51f /init
parent31b7eab27a314b153d8fa07ba9e9ec00a98141e1 (diff)
parent6506cf6ce68d78a5470a8360c965dafe8e4b78e3 (diff)
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Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (52 commits) sched: fix RCU lockdep splat from task_group() rcu: using ACCESS_ONCE() to observe the jiffies_stall/rnp->qsmask value sched: suppress RCU lockdep splat in task_fork_fair net: suppress RCU lockdep false positive in sock_update_classid rcu: move check from rcu_dereference_bh to rcu_read_lock_bh_held rcu: Add advice to PROVE_RCU_REPEATEDLY kernel config parameter rcu: Add tracing data to support queueing models rcu: fix sparse errors in rcutorture.c rcu: only one evaluation of arg in rcu_dereference_check() unless sparse kernel: Remove undead ifdef CONFIG_DEBUG_LOCK_ALLOC rcu: fix _oddness handling of verbose stall warnings rcu: performance fixes to TINY_PREEMPT_RCU callback checking rcu: upgrade stallwarn.txt documentation for CPU-bound RT processes vhost: add __rcu annotations rcu: add comment stating that list_empty() applies to RCU-protected lists rcu: apply TINY_PREEMPT_RCU read-side speedup to TREE_PREEMPT_RCU rcu: combine duplicate code, courtesy of CONFIG_PREEMPT_RCU rcu: Upgrade srcu_read_lock() docbook about SRCU grace periods rcu: document ways of stalling updates in low-memory situations rcu: repair code-duplication FIXMEs ...
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig26
1 files changed, 22 insertions, 4 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 2de5b1cbadd..a619a1ac7f4 100644
--- 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
@@ -365,8 +366,22 @@ 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
@@ -387,9 +402,12 @@ 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.