From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 68EE93ED5A2; Tue, 31 Mar 2026 09:23:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774949013; cv=none; b=EgywzwxfqBrUVN8njvL6ZCKK469yZPfPyA7KdQv0DzOw6jbhzOn9h7MvHO8oTaf2vckgS/NuwuzE8iJq4WvLIjzTdL5ZWf4TRo0bL345P6oniQpOjRTcWgiAOrMdVj3i7YoYeo7EwzujkJ7b7bDpPisoJO8AsuTU07/qCceMhTc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774949013; c=relaxed/simple; bh=DZoalaXDsEVeM0Ax8G7Y4p1iyVXciubggMHPstxJdjM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=E53QGCyCQzBNM4HbO3+XgRKQN/HY0Rjy1xSLug4EyFoa/+fdfb17Lt5o3B/m1FEwpAz/sq2h/c/W8CqO81rS5F+XLZpNOIjad8otYrZVn1M98QbsMpOFw1qwpfF3XAh+LH4snNTwibe9cztUlHqISl6Vp8dE+IJSXDIuWnUs3Yo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VWXHPvWT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VWXHPvWT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 98B8EC2BCB0; Tue, 31 Mar 2026 09:23:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774949013; bh=DZoalaXDsEVeM0Ax8G7Y4p1iyVXciubggMHPstxJdjM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VWXHPvWTOsXVqPgKgqy/3aAuIYHbb34PxPrQWaDkov23mCpqJs6NlSRh+dph649hd e+8MWiREWOuaVmDH4IiVTzViJCfMWPn0vRaCHcVLhNyd71rWE+oGzmtHxpndEjfaGJ ib94XthMSGL/K9/f45oGTA0BJ+CZilG4W+CMBVhmEqpWYD7iyt+Z8znthOg9rQQtBi PwBkYAMs0fKRCgPUiACMThrOPBUCtLx+NLZhBExu8TG+DLqi3NZKaTLn2wJN+rsQJ0 /oeXzSpdaZsbKUZSOX7GNIEkw6ZnazXlfbZ/+YIHyb+weE4txyZ4HZ6DOrzJi5x33I g1n84rD80/QTA== Date: Tue, 31 Mar 2026 11:23:30 +0200 From: Frederic Weisbecker To: Qiliang Yuan Cc: peterz@infradead.org, longman@redhat.com, cgroups@vger.kernel.org, akpm@linux-foundation.org, anna-maria@linutronix.de, boqun.feng@gmail.com, bsegall@google.com, dietmar.eggemann@arm.com, hannes@cmpxchg.org, jackmanb@google.com, jiangshanlai@gmail.com, joelagnelf@nvidia.com, josh@joshtriplett.org, juri.lelli@redhat.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, mathieu.desnoyers@efficios.com, mgorman@suse.de, mhocko@suse.com, mingo@kernel.org, mingo@redhat.com, neeraj.upadhyay@kernel.org, paulmck@kernel.org, qiang.zhang@linux.dev, rcu@vger.kernel.org, rostedt@goodmis.org, shuah@kernel.org, surenb@google.com, tglx@kernel.org, tj@kernel.org, urezki@gmail.com, vbabka@suse.cz, vincent.guittot@linaro.org, vschneid@redhat.com, ziy@nvidia.com Subject: Re: [PATCH 01/15] sched/isolation: Support dynamic allocation for housekeeping masks Message-ID: References: <20260325135707.GZ3738786@noisy.programming.kicks-ass.net> <20260330114348.102265-1-realwujing@gmail.com> Precedence: bulk X-Mailing-List: cgroups@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: <20260330114348.102265-1-realwujing@gmail.com> Le Mon, Mar 30, 2026 at 07:43:21PM +0800, Qiliang Yuan a écrit : 11;rgb:2e2e/3434/3636> Hi Peter, > > On Wed, Mar 25, 2026 at 02:57:07PM +0100, Peter Zijlstra wrote: > > 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? > > That's a fair point. For the vast majority of use cases (like NOHZ_FULL), > these masks are indeed identical and should be updated as a single unit. > > The original motivation for separation was to allow extreme fine-tuning in > HFT environments—for example, offloading RCU callbacks to keep a core > mostly clean but allowing pinned timers for specific localized > telemetry/monitoring. > > However, I acknowledge this adds significant complexity. In V13, I will > unify these into a single "Global Housekeeping Mask" by default to > simplify the configuration space, while keeping the underlying notifier > infrastructure flexible enough for future specialized needs. More precisely we only need four flags: HK_TYPE_DOMAIN_BOOT (isolcpus=) HK_TYPE_DOMAIN (cgroup v2 isolated partition + isolcpus=) HK_TYPE_KERNEL_NOISE (nohz_full=) HK_TYPE_MANAGED_IRQ (isolcpus=managed_irq) All the aliases of HK_TYPE_KERNEL_NOISE need to be renamed to HK_TYPE_KERNEL_NOISE. Thanks. -- Frederic Weisbecker SUSE Labs