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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-12-28 11:30:36 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-03-26 08:04:51 -0700
commitc0f4dfd4f90f1667d234d21f15153ea09a2eaa66 (patch)
treee06fa6eef015a373849855249752ec525ca8ad4b /Documentation/kernel-parameters.txt
parentb11cc5760a9c48c870ad286e8a6d8fdb998fa58d (diff)
rcu: Make RCU_FAST_NO_HZ take advantage of numbered callbacks
Because RCU callbacks are now associated with the number of the grace period that they must wait for, CPUs can now take advance callbacks corresponding to grace periods that ended while a given CPU was in dyntick-idle mode. This eliminates the need to try forcing the RCU state machine while entering idle, thus reducing the CPU intensiveness of RCU_FAST_NO_HZ, which should increase its energy efficiency. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt28
1 files changed, 19 insertions, 9 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a17ba16c8fc8..22303b2e74bc 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2490,6 +2490,17 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
leaf rcu_node structure. Useful for very large
systems.
+ rcutree.jiffies_till_first_fqs= [KNL,BOOT]
+ Set delay from grace-period initialization to
+ first attempt to force quiescent states.
+ Units are jiffies, minimum value is zero,
+ and maximum value is HZ.
+
+ rcutree.jiffies_till_next_fqs= [KNL,BOOT]
+ Set delay between subsequent attempts to force
+ quiescent states. Units are jiffies, minimum
+ value is one, and maximum value is HZ.
+
rcutree.qhimark= [KNL,BOOT]
Set threshold of queued
RCU callbacks over which batch limiting is disabled.
@@ -2504,16 +2515,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
Set timeout for RCU CPU stall warning messages.
- rcutree.jiffies_till_first_fqs= [KNL,BOOT]
- Set delay from grace-period initialization to
- first attempt to force quiescent states.
- Units are jiffies, minimum value is zero,
- and maximum value is HZ.
+ rcutree.rcu_idle_gp_delay= [KNL,BOOT]
+ Set wakeup interval for idle CPUs that have
+ RCU callbacks (RCU_FAST_NO_HZ=y).
- rcutree.jiffies_till_next_fqs= [KNL,BOOT]
- Set delay between subsequent attempts to force
- quiescent states. Units are jiffies, minimum
- value is one, and maximum value is HZ.
+ rcutree.rcu_idle_lazy_gp_delay= [KNL,BOOT]
+ Set wakeup interval for idle CPUs that have
+ only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
+ Lazy RCU callbacks are those which RCU can
+ prove do nothing more than free memory.
rcutorture.fqs_duration= [KNL,BOOT]
Set duration of force_quiescent_state bursts.