path: root/init/Kconfig
diff options
Diffstat (limited to 'init/Kconfig')
1 files changed, 37 insertions, 2 deletions
diff --git a/init/Kconfig b/init/Kconfig
index a92f27da4a27..4119a44e4157 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -526,6 +526,35 @@ config SRCU
permits arbitrary sleeping or blocking within RCU read-side critical
+ 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 TINY_RCU && !CLASSIC_SRCU
+ help
+ This option selects the single-CPU non-preemptible version of SRCU.
+config TREE_SRCU
+ bool
+ default y if !TINY_RCU && !CLASSIC_SRCU
+ help
+ This option selects the full-fledged version of SRCU.
config TASKS_RCU
default n
@@ -612,11 +641,17 @@ 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.