Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar:
 "The main changes in this cycle are mostly related to preparatory work
  for the full-dynticks work:

   - Remove restrictions on no-CBs CPUs, make RCU_FAST_NO_HZ take
     advantage of numbered callbacks, do callback accelerations based on
     numbered callbacks.  Posted to LKML at
        https://lkml.org/lkml/2013/3/18/960

   - RCU documentation updates.  Posted to LKML at
        https://lkml.org/lkml/2013/3/18/570

   - Miscellaneous fixes.  Posted to LKML at
        https://lkml.org/lkml/2013/3/18/594"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  rcu: Make rcu_accelerate_cbs() note need for future grace periods
  rcu: Abstract rcu_start_future_gp() from rcu_nocb_wait_gp()
  rcu: Rename n_nocb_gp_requests to need_future_gp
  rcu: Push lock release to rcu_start_gp()'s callers
  rcu: Repurpose no-CBs event tracing to future-GP events
  rcu: Rearrange locking in rcu_start_gp()
  rcu: Make RCU_FAST_NO_HZ take advantage of numbered callbacks
  rcu: Accelerate RCU callbacks at grace-period end
  rcu: Export RCU_FAST_NO_HZ parameters to sysfs
  rcu: Distinguish "rcuo" kthreads by RCU flavor
  rcu: Add event tracing for no-CBs CPUs' grace periods
  rcu: Add event tracing for no-CBs CPUs' callback registration
  rcu: Introduce proper blocking to no-CBs kthreads GP waits
  rcu: Provide compile-time control for no-CBs CPUs
  rcu: Tone down debugging during boot-up and shutdown.
  rcu: Add softirq-stall indications to stall-warning messages
  rcu: Documentation update
  rcu: Make bugginess of code sample more evident
  rcu: Fix hlist_bl_set_first_rcu() annotation
  rcu: Delete unused rcu_node "wakemask" field
  ...

1 files changed, 24 insertions, 11 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 12bbce346d58..de12397b60a9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2499,9 +2499,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         In kernels built with CONFIG_RCU_NOCB_CPU=y, set
                         the specified list of CPUs to be no-callback CPUs.
                         Invocation of these CPUs' RCU callbacks will
-                        be offloaded to "rcuoN" kthreads created for
-                        that purpose.  This reduces OS jitter on the
+                        be offloaded to "rcuox/N" kthreads created for
+                        that purpose, where "x" is "b" for RCU-bh, "p"
+                        for RCU-preempt, and "s" for RCU-sched, and "N"
+                        is the CPU number.  This reduces OS jitter on the
                         offloaded CPUs, which can be useful for HPC and
+
                         real-time workloads.  It can also improve energy
                         efficiency for asymmetric multiprocessors.
 
@@ -2525,6 +2528,17 @@ 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.
@@ -2539,16 +2553,15 @@ 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.