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Subject[tip:sched/core] sched/isolation: Update nohz documentation to explain tick offload
Commit-ID:  083c6eeab2cc13894618d188b854f2fc6b5b2303
Gitweb: https://git.kernel.org/tip/083c6eeab2cc13894618d188b854f2fc6b5b2303
Author: Frederic Weisbecker <frederic@kernel.org>
AuthorDate: Wed, 21 Feb 2018 05:17:29 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 21 Feb 2018 09:49:10 +0100

sched/isolation: Update nohz documentation to explain tick offload

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

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-8-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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
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