rcu: Provide diagnostic option to slow down grace-period initialization
Grace-period initialization normally proceeds quite quickly, so
that it is very difficult to reproduce races against grace-period
initialization. This commit therefore allows grace-period
initialization to be artificially slowed down, increasing
race-reproduction probability. A pair of new Kconfig parameters are
provided, CONFIG_RCU_TORTURE_TEST_SLOW_INIT to enable the slowdowns, and
CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY to specify the number of jiffies
of slowdown to apply. A boot-time parameter named rcutree.gp_init_delay
allows boot-time delay to be specified. By default, no delay will be
applied even if CONFIG_RCU_TORTURE_TEST_SLOW_INIT is set.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bfcb1a6..94de410 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2968,6 +2968,12 @@
Set maximum number of finished RCU callbacks to
process in one batch.
+ rcutree.gp_init_delay= [KNL]
+ Set the number of jiffies to delay each step of
+ RCU grace-period initialization. This only has
+ effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT is
+ set.
+
rcutree.rcu_fanout_leaf= [KNL]
Increase the number of CPUs assigned to each
leaf rcu_node structure. Useful for very large