* [PATCH] Documentation/no_hz: Introduce "dyntick-idle mode" before using it
@ 2021-09-14 20:33 Borislav Petkov
2021-09-27 17:31 ` Jonathan Corbet
0 siblings, 1 reply; 2+ messages in thread
From: Borislav Petkov @ 2021-09-14 20:33 UTC (permalink / raw)
To: Jonathan Corbet; +Cc: Paul E. McKenney, Thomas Gleixner, linux-doc, LKML
From: Borislav Petkov <bp@suse.de>
The CONFIG_NO_HZ_IDLE paragraph is using "dyntick-idle mode" before
having defined it while the definition comes a couple of paragraphs
later.
That is leaving the reader with scratching head what that dyntick-idle
mode might be. Pull its definition up so that it is clear.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
Documentation/timers/no_hz.rst | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/Documentation/timers/no_hz.rst b/Documentation/timers/no_hz.rst
index 6cadad7c3aad..20ad23a6c618 100644
--- a/Documentation/timers/no_hz.rst
+++ b/Documentation/timers/no_hz.rst
@@ -70,6 +70,10 @@ interrupt. After all, the primary purpose of a scheduling-clock interrupt
is to force a busy CPU to shift its attention among multiple duties,
and an idle CPU has no duties to shift its attention among.
+An idle CPU that is not receiving scheduling-clock interrupts is said to
+be "dyntick-idle", "in dyntick-idle mode", "in nohz mode", or "running
+tickless". The remainder of this document will use "dyntick-idle mode".
+
The CONFIG_NO_HZ_IDLE=y Kconfig option causes the kernel to avoid sending
scheduling-clock interrupts to idle CPUs, which is critically important
both to battery-powered devices and to highly virtualized mainframes.
@@ -91,10 +95,6 @@ Therefore, systems with aggressive real-time response constraints often
run CONFIG_HZ_PERIODIC=y kernels (or CONFIG_NO_HZ=n for older kernels)
in order to avoid degrading from-idle transition latencies.
-An idle CPU that is not receiving scheduling-clock interrupts is said to
-be "dyntick-idle", "in dyntick-idle mode", "in nohz mode", or "running
-tickless". The remainder of this document will use "dyntick-idle mode".
-
There is also a boot parameter "nohz=" that can be used to disable
dyntick-idle mode in CONFIG_NO_HZ_IDLE=y kernels by specifying "nohz=off".
By default, CONFIG_NO_HZ_IDLE=y kernels boot with "nohz=on", enabling
--
2.29.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] Documentation/no_hz: Introduce "dyntick-idle mode" before using it
2021-09-14 20:33 [PATCH] Documentation/no_hz: Introduce "dyntick-idle mode" before using it Borislav Petkov
@ 2021-09-27 17:31 ` Jonathan Corbet
0 siblings, 0 replies; 2+ messages in thread
From: Jonathan Corbet @ 2021-09-27 17:31 UTC (permalink / raw)
To: Borislav Petkov; +Cc: Paul E. McKenney, Thomas Gleixner, linux-doc, LKML
Borislav Petkov <bp@alien8.de> writes:
> From: Borislav Petkov <bp@suse.de>
>
> The CONFIG_NO_HZ_IDLE paragraph is using "dyntick-idle mode" before
> having defined it while the definition comes a couple of paragraphs
> later.
>
> That is leaving the reader with scratching head what that dyntick-idle
> mode might be. Pull its definition up so that it is clear.
>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
> Documentation/timers/no_hz.rst | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
Applied, thanks.
jon
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-09-14 20:33 [PATCH] Documentation/no_hz: Introduce "dyntick-idle mode" before using it Borislav Petkov
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