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Date: Wed, 25 Mar 2026 14:57:07 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Qiliang Yuan <realwujing@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>, Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
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	Thomas Gleixner <tglx@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun.feng@gmail.com>,
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	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, Shuah Khan <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
	linux-mm@kvack.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 01/15] sched/isolation: Support dynamic allocation for
 housekeeping masks
Message-ID: <20260325135707.GZ3738786@noisy.programming.kicks-ass.net>
References: <20260325-dhei-v12-final-v1-0-919cca23cadf@gmail.com>
 <20260325-dhei-v12-final-v1-1-919cca23cadf@gmail.com>
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In-Reply-To: <20260325-dhei-v12-final-v1-1-919cca23cadf@gmail.com>

On Wed, Mar 25, 2026 at 05:09:32PM +0800, Qiliang Yuan wrote:
> The existing housekeeping infrastructure uses a single static cpumask
> for all isolation types. This prevents independent runtime
> reconfiguration of different services (like RCU vs. timers).

I think I asked this a while ago; why do we have more than one mask?
What is the actual purpose of being able to separate RCU from Timers?