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From: Frederic Weisbecker <frederic@kernel.org>
To: Gabriele Monaco <gmonaco@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Waiman Long <longman@redhat.com>
Subject: Re: [PATCH v10 1/8] timers/migration: Postpone online/offline callbacks registration to late initcall
Date: Thu, 7 Aug 2025 14:42:33 +0200	[thread overview]
Message-ID: <aJSfOf5e4BhAmj2g@localhost.localdomain> (raw)
In-Reply-To: <20250806093855.86469-2-gmonaco@redhat.com>

Le Wed, Aug 06, 2025 at 11:38:48AM +0200, Gabriele Monaco a écrit :
> From: Frederic Weisbecker <frederic@kernel.org>
> 
> During the early boot process, the default clocksource used for
> timekeeping is the jiffies. Better clocksources can only be selected
> once clocksource_done_booting() is called as an fs initcall.
> 
> NOHZ can only be enabled after that stage, making global timer migration
> irrelevant up to that point.
> 
> Therefore, don't bother with trashing the cache within that tree from
> the SMP bootup until NOHZ even matters.

I think I made a mistake with this sentence. Actually the timers are not
propagated to the tree before nohz is enabled. So the sentence should
actually be:

"The tree remains inactive before NOHZ is enabled anyway. Therefore it
makes sense to enable each CPUs to the tree only once that is setup."

Thanks.
-- 
Frederic Weisbecker
SUSE Labs

  reply	other threads:[~2025-08-07 12:42 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-06  9:38 [PATCH v10 0/8] timers: Exclude isolated cpus from timer migration Gabriele Monaco
2025-08-06  9:38 ` [PATCH v10 1/8] timers/migration: Postpone online/offline callbacks registration to late initcall Gabriele Monaco
2025-08-07 12:42   ` Frederic Weisbecker [this message]
2025-08-06  9:38 ` [PATCH v10 2/8] timers: Rename tmigr 'online' bit to 'available' Gabriele Monaco
2025-08-06  9:38 ` [PATCH v10 3/8] timers: Add the available mask in timer migration Gabriele Monaco
2025-08-06  9:38 ` [PATCH v10 4/8] timers: Use scoped_guard when setting/clearing the tmigr available flag Gabriele Monaco
2025-08-06  9:38 ` [PATCH v10 5/8] cgroup/cpuset: Rename update_unbound_workqueue_cpumask() to update_exclusion_cpumasks() Gabriele Monaco
2025-08-06  9:38 ` [PATCH v10 6/8] sched/isolation: Force housekeeping if isolcpus and nohz_full don't leave any Gabriele Monaco
2025-08-06 20:38   ` Waiman Long
2025-08-06  9:38 ` [PATCH v10 7/8] cgroup/cpuset: Fail if isolated and nohz_full don't leave any housekeeping Gabriele Monaco
2025-09-02 14:33   ` Frederic Weisbecker
2025-09-02 19:14   ` Waiman Long
2025-08-06  9:38 ` [PATCH v10 8/8] timers: Exclude isolated cpus from timer migration Gabriele Monaco

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