rcu: Make synchronize_srcu_expedited() fast if running readers

[mv-sheeva.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index 929adf6cb6b4ac8aa0151ff868ae0f8d128edd0a..35518243c4bdddf0f93ba5ab2aee4505db1f7e0b 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -488,6 +488,21 @@ config RCU_BOOST_DELAY
 
          Accept the default if unsure.
 
+config SRCU_SYNCHRONIZE_DELAY
+       int "Microseconds to delay before waiting for readers"
+       range 0 20
+       default 10
+       help
+         This option controls how long SRCU delays before entering its
+         loop waiting on SRCU readers.  The purpose of this loop is
+         to avoid the unconditional context-switch penalty that would
+         otherwise be incurred if there was an active SRCU reader,
+         in a manner similar to adaptive locking schemes.  This should
+         be set to be a bit longer than the common-case SRCU read-side
+         critical-section overhead.
+
+         Accept the default if unsure.
+
 endmenu # "RCU Subsystem"
 
 config IKCONFIG