From 0f41c0ddadfb3d5baffe62351c380e2881aacd58 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 10 Mar 2015 18:33:20 -0700 Subject: rcu: Provide diagnostic option to slow down grace-period scans Grace-period scans of the rcu_node combining tree normally proceed quite quickly, so that it is very difficult to reproduce races against them. This commit therefore allows grace-period pre-initialization and cleanup to be artificially slowed down, increasing race-reproduction probability. A pair of pairs of new Kconfig parameters are provided, RCU_TORTURE_TEST_SLOW_PREINIT to enable the slowing down of propagating CPU-hotplug changes up the combining tree along with RCU_TORTURE_TEST_SLOW_PREINIT_DELAY to specify the delay in jiffies, and RCU_TORTURE_TEST_SLOW_CLEANUP to enable the slowing down of the end-of-grace-period cleanup scan along with RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY to specify the delay in jiffies. Boot-time parameters named rcutree.gp_preinit_delay and rcutree.gp_cleanup_delay allow these delays to be specified at boot time. Signed-off-by: Paul E. McKenney --- Documentation/kernel-parameters.txt | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 61ab1628a057..10a4fb80c033 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2992,11 +2992,23 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Set maximum number of finished RCU callbacks to process in one batch. + rcutree.gp_cleanup_delay= [KNL] + Set the number of jiffies to delay each step of + RCU grace-period cleanup. This only has effect + when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set. + 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. + effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT + is set. + + rcutree.gp_preinit_delay= [KNL] + Set the number of jiffies to delay each step of + RCU grace-period pre-initialization, that is, + the propagation of recent CPU-hotplug changes up + the rcu_node combining tree. This only has effect + when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set. rcutree.rcu_fanout_leaf= [KNL] Increase the number of CPUs assigned to each -- cgit v1.2.1