[PATCH 6/6] sched/isolation: Update nohz documentation to explain tick offload

From: Frederic Weisbecker
Date: Wed Feb 14 2018 - 19:48:50 EST


Update the documentation to reflect the 1Hz tick offload changes.

Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Wanpeng Li <kernellwp@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1d1d53f..50b9837 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
--
2.7.4