Merge git://git.infradead.org/users/willy/linux-nvme

[karo-tx-linux.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index fed81b576f29ad8003c48ed293bb9cd42bd95922..0a2c4bcf179e21d321b25206718cb58aad722b54 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -470,6 +470,7 @@ config TREE_RCU
 config TREE_PREEMPT_RCU
        bool "Preemptible tree-based hierarchical RCU"
        depends on PREEMPT
+       select IRQ_WORK
        help
          This option selects the RCU implementation that is
          designed for very large SMP systems with hundreds or
@@ -527,13 +528,29 @@ config RCU_USER_QS
 config CONTEXT_TRACKING_FORCE
        bool "Force context tracking"
        depends on CONTEXT_TRACKING
-       default CONTEXT_TRACKING
+       default y if !NO_HZ_FULL
        help
-         Probe on user/kernel boundaries by default in order to
-         test the features that rely on it such as userspace RCU extended
-         quiescent states.
-         This test is there for debugging until we have a real user like the
-         full dynticks mode.
+         The major pre-requirement for full dynticks to work is to
+         support the context tracking subsystem. But there are also
+         other dependencies to provide in order to make the full
+         dynticks working.
+
+         This option stands for testing when an arch implements the
+         context tracking backend but doesn't yet fullfill all the
+         requirements to make the full dynticks feature working.
+         Without the full dynticks, there is no way to test the support
+         for context tracking and the subsystems that rely on it: RCU
+         userspace extended quiescent state and tickless cputime
+         accounting. This option copes with the absence of the full
+         dynticks subsystem by forcing the context tracking on all
+         CPUs in the system.
+
+         Say Y only if you're working on the developpement of an
+         architecture backend for the context tracking.
+
+         Say N otherwise, this option brings an overhead that you
+         don't want in production.
+
 
 config RCU_FANOUT
        int "Tree-based hierarchical RCU fanout value"