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authorLinus Torvalds <torvalds@linux-foundation.org>2017-05-10 09:50:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-10 10:30:46 -0700
commitde4d195308ad589626571dbe5789cebf9695a204 (patch)
tree77a6bd6946594ea4e7513aaa73009295530960a1 /init
parentdc9edaab90de9441cc28ac570b23b0d2bdba7879 (diff)
parent20652ed6e44f4963281b65209b917be86ac6765b (diff)
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Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar: "The main changes are: - Debloat RCU headers - Parallelize SRCU callback handling (plus overlapping patches) - Improve the performance of Tree SRCU on a CPU-hotplug stress test - Documentation updates - Miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (74 commits) rcu: Open-code the rcu_cblist_n_lazy_cbs() function rcu: Open-code the rcu_cblist_n_cbs() function rcu: Open-code the rcu_cblist_empty() function rcu: Separately compile large rcu_segcblist functions srcu: Debloat the <linux/rcu_segcblist.h> header srcu: Adjust default auto-expediting holdoff srcu: Specify auto-expedite holdoff time srcu: Expedite first synchronize_srcu() when idle srcu: Expedited grace periods with reduced memory contention srcu: Make rcutorture writer stalls print SRCU GP state srcu: Exact tracking of srcu_data structures containing callbacks srcu: Make SRCU be built by default srcu: Fix Kconfig botch when SRCU not selected rcu: Make non-preemptive schedule be Tasks RCU quiescent state srcu: Expedite srcu_schedule_cbs_snp() callback invocation srcu: Parallelize callback handling kvm: Move srcu_struct fields to end of struct kvm rcu: Fix typo in PER_RCU_NODE_PERIOD header comment rcu: Use true/false in assignment to bool rcu: Use bool value directly ...
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig43
1 files changed, 41 insertions, 2 deletions
diff --git a/init/Kconfig b/init/Kconfig
index a92f27da4a27..1d3475fc9496 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -521,11 +521,41 @@ config RCU_EXPERT
config SRCU
bool
+ default y
help
This option selects the sleepable version of RCU. This version
permits arbitrary sleeping or blocking within RCU read-side critical
sections.
+config CLASSIC_SRCU
+ bool "Use v4.11 classic SRCU implementation"
+ default n
+ depends on RCU_EXPERT && SRCU
+ help
+ This option selects the traditional well-tested classic SRCU
+ implementation from v4.11, as might be desired for enterprise
+ Linux distributions. Without this option, the shiny new
+ Tiny SRCU and Tree SRCU implementations are used instead.
+ At some point, it is hoped that Tiny SRCU and Tree SRCU
+ will accumulate enough test time and confidence to allow
+ Classic SRCU to be dropped entirely.
+
+ Say Y if you need a rock-solid SRCU.
+
+ Say N if you would like help test Tree SRCU.
+
+config TINY_SRCU
+ bool
+ default y if SRCU && TINY_RCU && !CLASSIC_SRCU
+ help
+ This option selects the single-CPU non-preemptible version of SRCU.
+
+config TREE_SRCU
+ bool
+ default y if SRCU && !TINY_RCU && !CLASSIC_SRCU
+ help
+ This option selects the full-fledged version of SRCU.
+
config TASKS_RCU
bool
default n
@@ -543,6 +573,9 @@ config RCU_STALL_COMMON
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 || TINY_SRCU || TREE_SRCU )
+
config CONTEXT_TRACKING
bool
@@ -612,11 +645,17 @@ config RCU_FANOUT_LEAF
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.
+ 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.
+ 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.