From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A880C1DED42; Wed, 23 Sep 2026 15:27:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790177256; cv=none; b=OYAv4YjFZxm2E9+VS7Ux/CrBEHJT4Jxa/XFgs6O6f2YpyB4HTdp2b/jEuCt3oTUzE6ewkYkFtb/fYSs3EL4Vs6BoOQ37YoJYdCk9NhA0AdWqFIB+2y8PNi1nJXwRSJGj0kMg35FKIXUtGFcmE9VEfqqgqhxEelZTK93ww/KnXvY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790177256; c=relaxed/simple; bh=ZmeWKlO1uWXNiNx33YICOyZm9UbJ6iEopwmUDEtFAN0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jiKUBBZluNM2PYF99XyWqD+ZqfNsj24rBbG1NAxCQzohXd4t/Ta7samPSgjw2/m9R6KvOHchX1d3Pfr6lIP3IU+4k9t7m5QsAYmkqz8xPVRbd2PhAJbOzzDA7+QtKNXuzIa78WwXaLCC4Bd+74pXdwh5Z8lkeePls/GX8oi0Tj0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jD6dvp/C; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jD6dvp/C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C0101F000FF; Wed, 23 Sep 2026 15:27:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790177249; bh=gKsiXERWQlR6rp9onnZUafQe9FGJ1g3zTuAUGmAFbnw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=jD6dvp/C6uPldzGalEI3E4WS2qhrxlqI6O4ZPYpP+Cu1fEJIXwq2aVH56QlV/0Jme 7sVMJfV7GmC0UaYErRA3Ug9AttKuZvYvlsQY17faNDwX/lkhou7dZb9WozungbiWDz c6Ln4RVr1ZImU4ftMon4mL0cu2+sNuR5+WGrZbDxIne8ftEPl0rWNQNoESD17gNn5x rSw6+gklNudhQnayOR555AQLV/CIXpkwV80n5Da0lFN8nG6/pGbnsGF9ypbaLyW4TI mrNmts/WGWeqxESg7mwl57+hGxfZtUaYc/zmkVJBi7RGZE8+FW8Fy4YO1YhhcAoiO8 BkxGgyOWPBHSQ== Date: Wed, 23 Sep 2026 17:27:26 +0200 From: Frederic Weisbecker To: Jing Wu Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Anna-Maria Behnsen , Tejun Heo , Jonathan Corbet , Shuah Khan , Shuah Khan , Thomas Gleixner , Waiman Long , linux-kernel@vger.kernel.org, rcu@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Qiliang Yuan Subject: Re: [PATCH v4 00/11] Dynamic Housekeeping Management (DHM) via CPUSets Message-ID: References: <20260710-wujing-dhm-v4-0-2e912e5d9645@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260710-wujing-dhm-v4-0-2e912e5d9645@gmail.com> Le Fri, Jul 10, 2026 at 11:28:11AM +0800, Jing Wu a écrit : > This series introduces Dynamic Housekeeping Management (DHM) to the Linux > kernel, enabling runtime reconfiguration of kernel-noise housekeeping > (nohz_full tick suppression, RCU NOCB offloading, and managed IRQ > migration) through the existing cgroup v2 cpuset isolated partition > mechanism — no new kernel ABI required. > > When a cpuset partition is set to isolated mode, DHM cycles each CPU in > that partition offline, reconfigures the housekeeping masks (removing the > CPU from HK_TYPE_KERNEL_NOISE and related types), and brings it back > online. The subsystems (tick/nohz, RCU NOCB, genirq) pick up the new > masks through their existing CPU hotplug callbacks. Destroying the > partition reverses the cycle: each CPU is taken offline, restored to all > housekeeping masks, and brought back online. > > Housekeeping cpumask pointers are RCU-protected to allow lock-free readers > during updates. A global dhm_cycling_cpus mask suppresses transient > cpuset partition invalidation while CPUs are being cycled. > > This work is related to Waiman Long's [PATCH-next 00/23] series > (20260421030351.281436-1-longman@redhat.com), which also targets runtime > cpuset housekeeping control. DHM's distinguishing feature is zero-boot- > parameter activation: nohz_full+nocb isolation can be achieved at runtime > without any boot-time nohz_full= or rcu_nocbs= parameters. > > Signed-off-by: Jing Wu > Signed-off-by: Qiliang Yuan Sorry for the delay, I'm finally on it. One thing I would like to have is to make HK_TYPE_KERNEL_NOISE to always be a superset of HK_TYPE_DOMAIN. Ie: Cpuset's nohz_full should imply isolated domain partition. Or to put it another way: a nohz_full CPU should always run on isolated domains. If I could do it again, I would enforce the boot nohz_full= to always be a subset of isolcpus=domain. But we didn't know the possible usecase of it at the time. Thanks. -- Frederic Weisbecker SUSE Labs