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authorIngo Molnar <mingo@kernel.org>2017-04-23 11:12:44 +0200
committerIngo Molnar <mingo@kernel.org>2017-04-23 11:12:44 +0200
commit58d30c36d472b75e8e9962d6a640be19d9389128 (patch)
treece161b15e844d081f527f02a4f74ffd1171b2b14 /init
parent94836ecf1e7378b64d37624fbb81fe48fbd4c772 (diff)
parentf2094107ac82bf867184efd77cee30b6a98e2e20 (diff)
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Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU updates from Paul E. McKenney: - Documentation updates. - Miscellaneous fixes. - Parallelize SRCU callback handling (plus overlapping patches). Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig39
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
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 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
bool
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.