[PATCH 3/3] Documentation: no_hz: Add tick stop in polling idle

[Marco Crivellari <marco.crivellari@suse.com>]

On nohz_full CPUs the scheduling-clock tick is stopped while polling.
Update the documentation accordingly.

Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
---
 Documentation/timers/no_hz.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/timers/no_hz.rst b/Documentation/timers/no_hz.rst
index 4006cab64079..d3ada4a0ebea 100644
--- a/Documentation/timers/no_hz.rst
+++ b/Documentation/timers/no_hz.rst
@@ -246,6 +246,9 @@ Known Issues
 		be even worse than that of dyntick-idle.  Furthermore,
 		this parameter effectively disables Turbo Mode on Intel
 		CPUs, which can significantly reduce maximum performance.
+		Note also that on nohz_full CPUs the scheduling-clock tick
+		is stopped while polling, so that it does not keep running
+		and interrupt the task once it resumes after idle.
 
 *	Adaptive-ticks slows user/kernel transitions slightly.
 	This is not expected to be a problem for computationally intensive
-- 
2.56.0