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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Gabriele Monaco <gmonaco@redhat.com>,
	Ingo Molnar <mingo@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Marco Crivellari <marco.crivellari@suse.com>,
	Michal Hocko <mhocko@kernel.org>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>, Phil Auld <pauld@redhat.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Valentin Schneider <vschneid@redhat.com>,
	Vlastimil Babka <vbabka@suse.cz>, Waiman Long <longman@redhat.com>,
	linux-doc@vger.kernel.org
Subject: Re: [PATCH] doc: Add CPU Isolation documentation
Message-ID: <20260324153823.VKwebBuG@linutronix.de>
References: <20250809094247.8384-1-frederic@kernel.org>
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In-Reply-To: <20250809094247.8384-1-frederic@kernel.org>

On 2025-08-09 11:42:47 [+0200], Frederic Weisbecker wrote:
=E2=80=A6
> --- /dev/null
> +++ b/Documentation/admin-guide/cpu-isolation.rst
> @@ -0,0 +1,338 @@
=E2=80=A6
> +CPUSET configuration (cgroup v2)
> +--------------------------------
> +
> +Assuming cgroup v2 is mounted to /sys/fs/cgroup, the following script
> +isolates CPU 7 from scheduler domains.
> +
> +  cd /sys/fs/cgroup
> +  # Activate the cpuset subsystem
> +  echo +cpuset > cgroup.subtree_control
> +  # Create partition to be isolated
> +  mkdir test
> +  cd test
> +  echo +cpuset > cgroup.subtree_control
> +  # Isolate CPU 7
> +  echo 7 > cpuset.cpus
> +  echo "isolated" > cpuset.cpus.partition

while looking at this again, shouldn't you also do
	echo 7 > cpuset.cpus.exclusive

to ensure the CPU isn't used somewhere else?

Sebastian