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

Pull scheduler updates from Ingo Molnar:
 "The main scheduler changes in this cycle were:

   - NUMA balancing improvements (Mel Gorman)

   - Further load tracking improvements (Patrick Bellasi)

   - Various NOHZ balancing cleanups and optimizations (Peter Zijlstra)

   - Improve blocked load handling, in particular we can now reduce and
     eventually stop periodic load updates on 'very idle' CPUs. (Vincent
     Guittot)

   - On isolated CPUs offload the final 1Hz scheduler tick as well, plus
     related cleanups and reorganization. (Frederic Weisbecker)

   - Core scheduler code cleanups (Ingo Molnar)"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits)
  sched/core: Update preempt_notifier_key to modern API
  sched/cpufreq: Rate limits for SCHED_DEADLINE
  sched/fair: Update util_est only on util_avg updates
  sched/cpufreq/schedutil: Use util_est for OPP selection
  sched/fair: Use util_est in LB and WU paths
  sched/fair: Add util_est on top of PELT
  sched/core: Remove TASK_ALL
  sched/completions: Use bool in try_wait_for_completion()
  sched/fair: Update blocked load when newly idle
  sched/fair: Move idle_balance()
  sched/nohz: Merge CONFIG_NO_HZ_COMMON blocks
  sched/fair: Move rebalance_domains()
  sched/nohz: Optimize nohz_idle_balance()
  sched/fair: Reduce the periodic update duration
  sched/nohz: Stop NOHZ stats when decayed
  sched/cpufreq: Provide migration hint
  sched/nohz: Clean up nohz enter/exit
  sched/fair: Update blocked load from NEWIDLE
  sched/fair: Add NOHZ stats balancing
  sched/fair: Restructure nohz_balance_kick()
  ...

1 files changed, 11 insertions, 0 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1d1d53f85ddd..50b9837e985b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1766,6 +1766,17 @@
 
 			nohz
 			  Disable the tick when a single task runs.
+
+			  A residual 1Hz tick is offloaded to workqueues, which you
+			  need to affine to housekeeping through the global
+			  workqueue's affinity configured via the
+			  /sys/devices/virtual/workqueue/cpumask sysfs file, or
+			  by using the 'domain' flag described below.
+
+			  NOTE: by default the global workqueue runs on all CPUs,
+			  so to protect individual CPUs the 'cpumask' file has to
+			  be configured manually after bootup.
+
 			domain
 			  Isolate from the general SMP balancing and scheduling
 			  algorithms. Note that performing domain isolation this way