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Message-ID: <164182000439.16921.4167002233119575414.tip-bot2@tip-bot2>
Date: Mon, 10 Jan 2022 13:06:44 -0000
From: "tip-bot2 for Waiman Long" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Paul E. McKenney" <paulmck@...nel.org>,
Waiman Long <longman@...hat.com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: timers/core] clocksource: Reduce the default
clocksource_watchdog() retries to 2
The following commit has been merged into the timers/core branch of tip:
Commit-ID: 1a5620671a1b6fd9cc08761677d050f1702f910c
Gitweb: https://git.kernel.org/tip/1a5620671a1b6fd9cc08761677d050f1702f910c
Author: Waiman Long <longman@...hat.com>
AuthorDate: Thu, 18 Nov 2021 14:14:37 -05:00
Committer: Paul E. McKenney <paulmck@...nel.org>
CommitterDate: Tue, 30 Nov 2021 17:22:29 -08:00
clocksource: Reduce the default clocksource_watchdog() retries to 2
With the previous patch, there is an extra watchdog read in each retry.
Now the total number of clocksource reads is increased to 4 per iteration.
In order to avoid increasing the clock skew check overhead, the default
maximum number of retries is reduced from 3 to 2 to maintain the same 12
clocksource reads in the worst case.
Suggested-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Waiman Long <longman@...hat.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
Documentation/admin-guide/kernel-parameters.txt | 4 ++--
kernel/time/clocksource.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9725c54..3ea934b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -603,8 +603,8 @@
clocksource.max_cswd_read_retries= [KNL]
Number of clocksource_watchdog() retries due to
external delays before the clock will be marked
- unstable. Defaults to three retries, that is,
- four attempts to read the clock under test.
+ unstable. Defaults to two retries, that is,
+ three attempts to read the clock under test.
clocksource.verify_n_cpus= [KNL]
Limit the number of CPUs checked for clocksources
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index bcad1a1..b7e52a6 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -199,7 +199,7 @@ void clocksource_mark_unstable(struct clocksource *cs)
spin_unlock_irqrestore(&watchdog_lock, flags);
}
-ulong max_cswd_read_retries = 3;
+ulong max_cswd_read_retries = 2;
module_param(max_cswd_read_retries, ulong, 0644);
EXPORT_SYMBOL_GPL(max_cswd_read_retries);
static int verify_n_cpus = 8;
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