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@xxxxxxxxxx> AuthorDate: Thu, 18 Nov 2021 14:14:37 -05:00 Committer: Paul E. McKenney <paulmck@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Waiman Long <longman@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- 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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