linux-kernel - [tip:sched/core] sched/isolation: Update nohz documentation to explain tick offload

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Wed, 21 Feb 2018 02:38:21 -0800
From:   tip-bot for Frederic Weisbecker <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     frederic@...nel.org, riel@...hat.com, cmetcalf@...lanox.com,
        torvalds@...ux-foundation.org, cl@...ux.com,
        paulmck@...ux.vnet.ibm.com, kernellwp@...il.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, lcapitulino@...hat.com,
        tglx@...utronix.de, hpa@...or.com, peterz@...radead.org,
        efault@....de
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@...nel.org>
AuthorDate: Wed, 21 Feb 2018 05:17:29 +0100
Committer:  Ingo Molnar <mingo@...nel.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@...nel.org>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Cc: Chris Metcalf <cmetcalf@...lanox.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@...hat.com>
Cc: Mike Galbraith <efault@....de>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Wanpeng Li <kernellwp@...il.com>
Link: http://lkml.kernel.org/r/1519186649-3242-8-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.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