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Message-Id: <20210422120158.33629-6-frederic@kernel.org>
Date: Thu, 22 Apr 2021 14:01:55 +0200
From: Frederic Weisbecker <frederic@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
Frederic Weisbecker <frederic@...nel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Yunfeng Ye <yeyunfeng@...wei.com>,
Marcelo Tosatti <mtosatti@...hat.com>
Subject: [PATCH 5/8] tick/nohz: Update nohz_full Kconfig help
CONFIG_NO_HZ_FULL behaves just like CONFIG_NO_HZ_IDLE by default.
Reassure distros about it.
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Yunfeng Ye <yeyunfeng@...wei.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
kernel/time/Kconfig | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 83e158d016ba..6649e1d2dba5 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -117,13 +117,14 @@ config NO_HZ_FULL
the task mostly runs in userspace and has few kernel activity.
You need to fill up the nohz_full boot parameter with the
- desired range of dynticks CPUs.
+ desired range of dynticks CPUs to use it. This is implemented at
+ the expense of some overhead in user <-> kernel transitions:
+ syscalls, exceptions and interrupts.
- This is implemented at the expense of some overhead in user <-> kernel
- transitions: syscalls, exceptions and interrupts. Even when it's
- dynamically off.
+ By default, without passing nohz_full parameter, this behaves just
+ like NO_HZ_IDLE.
- Say N.
+ If you're a distro say Y.
endchoice
--
2.25.1
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